so lets look at what has been admitted, at least, for the animals favoured for profitable clone development. firstly it is known that cloning will reduce their lifespan, and lead to an increase and sooner development of age related diseases.
an exerpt from an article published on the australian abc website, thursday 27 may 1999.
"Dolly the sheep has DNA damage that might cause premature ageing, according to research by scientists who created the clone in 1996. The team from the Scottish biotechnology firm PPL Therapeutics has found Dolly and two other cloned sheep have shorter than normal telomeres - sections of DNA at the end of chromosomes thought to be involved in ageing.
Telomeres have been likened to the protective caps on the ends of shoelaces that prevent the lace from unravelling over time. Only in living cells, it's thought the telomeres on the ends of chromosomes become progressively shorter with multiple cell divisions, until they reach a point when the chromosomes become unstable and prone to damage. This may be a mechanism to ensure the death of cells once they reach a certain age.
In today's Nature, the team report that Dolly, who was cloned from a cell taken from a six-year-old sheep, had telomeres about 20 per cent shorter than other sheep of a similar age conceived naturally. The finding is not unexpected because cells used for cloning have to be cultured - allowed to divide many times in laboratory dishes - a process that is known to shorten telomeres. And in Dolly's case, the shortening was compounded because she was derived from a cell from a middle-aged animal. But the confirmation is of interest because it should allow scientists to test theories linking shortened telomeres with premature ageing.
PPL's research director, Alan Coleman, said the team had not observed any signs of premature ageing in Dolly yet, but he conceded they might show up later. He says it is impossible to predict precisely how long the world famous sheep will live. It is not known what length of telomere is critical for life. Previous studies by researchers in the United States have shown mice bred to have shorter telomeres, did indeed show premature ageing - their hair turned grey, they developed cancers and died earlier than usual..."
"If the telomere theory is proven correct, it may place limits on the potential of exciting new medical technology arising from developments in cloning. Hopes of taking master cells from cloned human embryos and growing them into perfectly matched organs for transplant surgery could be thwarted if the process of creating the organs left them with a short life."
oh yes. as usual, only foisting commercial applications on an unsuspecting world will make up for the billions spent. in the end some justification of budget has to be sought... (from an article published monday 3rd july 2006)
"It later emerged that the same team, managed by Ian Wilmut, had previously created two sheep clones from embryonic cells. So, strictly speaking, Dolly was the first mammal to be successfully cloned from an adult cell.
Not all good news
After this breakthrough, other cloned species swiftly followed: horses, bulls, pigs, mice, rats, rabbits, cats and dogs and others. But the miscarriage rate of transplanted eggs is extremely high, and of those embryos that make it to term, many have deformities or, as happened with Dolly, die prematurely, a clear warning to any scientist mad or foolish enough to try to make a cloned baby.
The suspected cause is that the genetic software isn't transferred entirely, or is somehow damaged in the transfer. As a result, the machinery malfunctions - genes don't switch on or off as they should in the complex ballet of making proteins."
Dolly the cloned sheep, by the way, died at the ripe old age of six, barely reaching half the average lifespan of her more natural cousins. from the wikipedia website -
"Dolly (July 5, 1996 – February 14, 2003), a female sheep or ewe, was the first mammal to be cloned from an adult somatic cell, using the process of nuclear transfer. The cell used was a mammary gland , proving that a cell taken from a specific body part could create a whole individual. She was named Dolly after the curvaceous country western singer Dolly Parton. Previously it was believed that a specific cell could only produce replicas of the same body part from which it was obtained. She was cloned by Ian Wilmut, Keith Campbell and colleagues at the Roslin Institute in Edinburgh, Scotland, and lived there until her death at age six. Her birth was announced in February 1997."
"On November 11, 2003 it was announced that Dolly had been euthanised because of a progressive lung disease and crippling arthritis. A Finn Dorset such as Dolly would have had a life expectancy of around 12 - 15 years."
the autopsy concluded that dolly did not die as a result of being a clone. however she developed diseases only aged sheep were prone to suffer. remember she was cloned from a six year old sheep. so at the age of seven, genetically she was already 13 years old.
those flaws are genetic. they would be passed onto any and all offspring, threatening their genetic 'stability' generation to generation. a cascading of congenital deformities which with further cloning/inbreeding would only become both more numerous and more complex.
