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مدیر وبلاگ : حمیده شیخ زین الدین
A brief introduction to cloning
Mention cloning to anyone and they will probably think of a little sheep called Dolly and a mad professor in a white apron. But the world of cloning has been going on a lot longer than most people realise and the crazy scientists have been really really busy. So here, after a brief introduction to cloning, is a list of some of the fake animals we know about that.
A brief introduction to cloning
The cloning of animals you're thinking about is normally a specific form of cloning called somatic cell nuclear transfer (SCNT). A somatic cell is any cell in the body except sperm cells or the egg cells. Each somatic cell has two sets of chromosomes. The idea is kind of simple. Take a somatic cell from an adult animal. Remove its nucleus - the brain of the cell containing the DNA which makes the animal the way it is, then take an empty nucleus-less egg cell and insert the DNA inside it. Then do a little bit of laboratory business and insert the new egg into a surrogate mother animal. After gestation a new animal is born exactly the same as the animal which donated its DNA. Weird, yes. Incredible, yes.
Injaz the Camel
In April 2009 Injaz, or 'Achievement' in English, became the world's first ever cloned camel. Injaz, a female one-humped camel, was born in Dubai on April 8, 2009 at the city's Camel Reproduction Centre following investment from Sheikh Mohammed bin Rashid al-Maktoum - he of international horse racing fame. Injaz's real mother was slaughtered for camel meat in 2005, but scientists saved the DNA and injected it into an empty egg cell of Injaz's surrogate camel mother. With camel racing big business in Dubai the implications of camel cloning are significant. And if you're thinking you've heard of the Camel Reproduction Centre before it's because it produced the world's first ever Cama, a Camel Llama hybrid.
The Cloned Carp
If you thought cloning was a relatively new phenomenon then you were wrong. Depending of course on your view of the word 'relatively'. Because cloning was going on way back in the 60s. In China an embryologist called Tong Dizhou cloned a carp. It was the world's first ever cloned fish and the first time such a complex organism had ever been cloned. Then ten years later he inserted the DNA of an Asian carp into a European carp mother - the world's first ever cross carp. Although if you keep them out of water long enough...
Unfortunately for Europeans much of Dr Dizhou's work was never translated into English meaning Western scientists had no idea such advances were being made.
Carbon Copy Cat
Carbon Copy or Cc surprised everyone when she was born because she didn't look or act anything like her genetic mum. For a start she had a grey stripe running down her white back whereas her mother, Rainbow, sported more of a gold and brown style. Then, when Cc started to play, she was found to be rather frisky. Rainbow on the other hand had always been shy and disinterested. Rainbow was quite a solid kitty. Cc was sleek. And so the illusion of cloning was smashed. But not for the makers of Cc. Genetic Savings and Clone claimed this was evidence of what they had stated all along, that cloned cats and dogs don't arrive with all the old tricks. Still for a company taking a mere $1000 from deluded pet owners seeking to revive their beloved dead pets it was all a bit of a nuisance.
Daisy, Millie, Emma - The Cloned Cows
Cow cloning has been going strong for a number of years although just what that number is appears to be a bit of a mystery. Japan claimed to have produced the world's first cloned cows when in July 1998 a pair of calves were born using the same technique that produced Dolly the Sheep a year before.
One very important cow was born on July 7 1999. Daisy (the calf pictured above), a Holston heifer, was cloned from a 13-year-old cow named Aspen. Scientists had often worried that cloning the DNA of an elderly animal would result in health problems for the newborn animal. But Daisy proved doubters wrong when she was able to give birth naturally two years later.
Jersey females Millie and Emma were cloned in 2001 using standard cell-culturing, a slightly different technique to the 'Dolly The Sheep cloning' of most animals. Emma, an acronym of Experimental Manipulation of Mastitis Abatement, was born to help scientists discover the genetic susceptibility to the bovine disease mastitis. Cow cloning is money with improved beef and milk yields sought across the world. Unfortunately Millie died. But then what hope have you got if you're born a cow?
Dewey the Deer
Dewey became the world's first ever cloned deer when he was born on May 23 2003 at the College of Veterinary Medicine in Texas. Dewey is a white-tailed deer and became the fifth animal the college had successfully cloned, the others being a pig, cattle, goats and a cat. Dewey is a copy of a male white-tailed deer from southern Texas. He was created using fibroplast cells which were isolated from skin samples derived from the dead buck, expanded in culture then frozen and stored in nitrogen. And best of all he's quite cute, isn't he?
Snuppy the Afghan Hound
In Korea people eat dogs, so it was something of a surprise when in August 2005 scientists announced to the world they had successfully created the world's first ever cloned canine, Snuppy. No, not Snoopy. Snuppy. It was a long and difficult process with scientists using nearly 2000 eggs to produce 1095 cloned embryos which were inserted into 123 dogs. Of these only three became pregnant and of these one miscarried, one was born but died after only 22 days, and then there was Snuppy, an apparently healthy cloned Afghan Hound born by a Golden Retriever!
The world later woke to the shock news that Korean stem cellscientist Dr Woo Suk Hwang had fabricated each of his major discoveries, all that is apart from Snuppy. Good boy.
Libby and Lilly Ferret
Libby and Lilly became the first cloned ferrets in 2004 to apparently help scientists study human respiratory diseases. Yes, your respiratory system is the same as a ferret's. Lovely.
The Cloned Tadpole
Scientist John Gurdon claimed he cloned tadpoles way back in the 1970s. In techniques that would later be developed to clone Dolly, Gurdon successfully transplanted the nucleus of one frog into the egg cell of another. There has since been some scepticism surrounding the success of Gurdon's attempts and it's true that none of his tadpoles ever made it into frogs. But what he did do was show what could and would later be done. If that makes sense.
Mira, Mira and Mira - The Three Goats
America cloned goats first in 1999. And to prove it they gave them all the same name. Mira and Mira and Mira were all born within two months of each other. The aim was medical. The three Mira's were created to produce a substance called antithrombin III in their milk, a protein which stops human blood clotting.
Noah the Gaur
Unfortunately Noah, the first endangered animal clone, died shortly after his birth. The baby bull gaur (a wild ox native to Asia) was born in January 2001 but due to complications surrounding his birth lived for only 48 hours. He died after suffering dysentery. It was a blow for scientists hoping to use cloning to save animals from extinction. But they're still trying.
Prometea the Horse
Born on May 28 2003 Prometea (the female version of Prometheus) became the world's first cloned horse. The Laboratory of Reproductive Technology in Italy created 841 embryos of which only 14 could be used and only four were implanted into surrogate mothers. Only Prometea the Halfinger foal was born. Horse racing has so far said no to cloning preferring the more traditional methods of reproduction but with millions of pounds being made on the mating rights of horses surely cloning is the nearly natural next step.
Masha the Mouse
So the sheep might have gotten all the fame but it was Masha the Mouse who really paved the way for mammal cloning. Back in 1986 Russian scientists Chaylakhyan, Veprencev, Sviridova and Nikitin cloned Masha from an embryo cell.
Much later, in December 1997 in Hawaii, a mouse called Cumulina (pictured above) became the first mouse to be cloned from an adult cell. During her life she gave birth to two litters and died naturally in her sleep in 2000.
Little Idaho Gem celebrated a double when he was born in May 2003 becoming both the world's first cloned mule and the world's first clone related to the horse family. Financed by a wealthy mule-racing magnate, Idaho Gem, along with another cloned mule, Idaho Star, was sent to a trainer for a successful career on the track.
The Five Little Pigs
Pigs and humans have more in common than a bacon sandwich. In fact the animals are now extremely important as providers of organs for human transplants. On March 5, 2000 an Edinburgh-based company called PPL Therapeutics announced it had successfully cloned five piglets - Millie, Christa, Alexis, Carrell and Dotcom. Since then science and technology have moved on and pigs are being specifically engineered so that their tissues are not rejected by the human body.
Dolly The Famous Sheep
The star of the show Dolly The Sheep, so famous her name is referred to in capitals, became an overnight sensation when in July 1996 she became the first ever mammal to be cloned from an adult somatic cell. However it wasn't until a year later that scientists mentioned the news to an ignorant and cynical public. Television channels were full of Dolly eating grass, Dolly looking at the camera, Dolly standing in hay. She became the most famous sheep ever to walk the planet and the planet loved her and hated her in equal measure. After six years at the top Dolly succumbed to illness and died. It was a sad end but a not unfamiliar story of the new celebrity age.
ANDi (inserted DNA, in reverse) was named as the first genetically modified monkey when he was born in October 2000. He was created specifically to carry one extra gene from another species. Born in the lab ANDi helped scientists pursue further tests for human diseases such as Alzheimer's, diabetes and heart disease.
Snuwolf and Snuwolffy
In October 2005 two wolves in Korea defied the laws of natural selection when they were successfully cloned to avoid extinction. Snuwolf and Snuwolffy were born in the Korea Zoo where they still live. Well one of them does. Unfortunately Snuwolf died in August 2009 from an infection which was absolutely nothing to do with the cloning process according to the scientists.
نوع مطلب : اصلاح دام و طیور، فیزیولوژی،
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سه شنبه 2 خرداد 1396 02:40 قبل از ظهر
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دوشنبه 28 فروردین 1396 10:13 بعد از ظهر
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