Clones.

[Digit]

http://news.sky.com/skynews/Home/UK-New ... _Last_Year

Many species, ours included, produce identical siblings, they are clones!

Roy.

 

[StevieB]

Sorry, monozygotic twins are not clones. They are the product of two parents and 100% genetically identical to neither. That they are identical to each other is becuase they have a single origin post-fertilisation, not because independent events have produced the same outcome. Identical twins - yes, clones - no.

Steve

 

[Digit]

Does the method of fertilisation define clones?
Identical siblings start as a single egg that then divides, fission, thus they are identical, this whether the fertilisation is as God defined or in a lab.
Only one egg is fertilised, if it divides naturally we call them twins, if done in a lab we call them clones.

Roy.

 

[StevieB]

No - lab defined cloning is where the offspring is 100% genetically identical to a single parent. Monozygotic twins are identical to only each other. The cloning refers to the parental origin, not the relatedness of other siblings.

Steve

 

[Digit]

I know that it is indeed less than 100 per cent Steve but you must understand that the term has been around for much longer than than man's interference.
If you look in an older dictionary the clones are identified as off spring from vegetative reproduction and asexual reproduction.
Even the modern usage of the term Fission for nuclear explosions etc is poached from biology.
Cloning of farm animals is simply a quicker means of obtaining 'desirable' traits than the previous practise of 'selective' breeding, but it gives the press something to put on the front page I suppose.

Roy.

 

[dickm]

True, Roy, that clones used to be defined as the product of vegetative reproduction (not much fun!), but that means, as Steve says, that the offspring is identical to the parent, not just to its siblings.
So you're both right!

 

[Digit]

The meaning appears to be changing/changed Dick.
But I think we're back to another thread of mine, people's lack of scientific knowledge. They accept selective breeding but react with horror at cloning, on Sky Net there were even claims that cloning spreads diseases, it can't spread what isn't already present!

Roy.

 

[StevieB]

Cloning of farm animals is simply a quicker means of obtaining 'desirable' traits than the previous practise of 'selective' breeding, but it gives the press something to put on the front page I suppose.

Roy.

Sorry to be a pedant, but wrong again - cloning doesn't obtain anything - it produces an exact copy. Thus selective breeding tries to retain or improve an existing trait or phenotype, cloning makes a copy of an existing trait or phenotype. Its slower and more restrictive than even selective breeding, and also a heck of alot more scientifically labour intensive. This will change with practice and time however, as does any process. The only problem with cloning in this instance is that alot of phenotypes are the product of gene-environment interactions - if you don't feed a pig it will not get a thick layer of fat no matter what its genetics as a trite example. Its also the reason why cloning Hitler wouldn't start another world war, and why cloning a new child with tissue from a dead child will not bring back the first child.

Selective breeding has been around for as long as farming and animal husbandry. Genetics just speeds it up a bit - if you know what gene codes for a trait then you can either add this into the genome of an animal or selectively breed offspring containing that gene. This is much faster than watching to see the trait develop in an adult animal. As a nice example consider dogs - all bred from the wolf as a common ancestor yet a poodle, a pug and a great dane are completely different through trait selection. The same principle extends to saviour siblings for disease states and selection of disease free offspring via pre-implantation screening for example where two parents carry the cystic fibrosis gene screen embroyos for the disease gene.

The issue with cloning is that because it is still a biological process, copies will never be identical at the base level. And a cloned organism will be subtly different from a normally produced offspring simply because cloning uses an adult cell and uses the genetic material from it to generate an embryo. As an example - each of your chromosomes has a section at the end called a telomere. This region gets shorter as cells divide and age, and some scientists suggests telomere length may be strongly related to aging overall. So if you take an adult cell and generate a clone with it, the clone has short telomeres also. What is the consequence of this for the clone when its 20 years old - nobody currently knows.

The original story related to cloned meat entering the foodchain. In theory, if the parental animal was suitable for the foodchain, so was the cloned offspring. Indeed the FDA in the US accepts cloned livestock as suitable to enter the foodchain. Europe does not. We had the same problems with GMOs. Anyone remember the FlavaSava tomato, or the Monsanto pesticide resistant wheat? The long term consequences of these are unknown. The FlavaSava tomato has the gene that controlled ripening of the fruit removed and spliced in backwards so the tomato didn't rot so quickly. The wheat has a pesticide resistance gene inserted so the wheat was resistant to a particular pesticide. You could then spray more pesticide on a wheat field to remove weeds without harming the wheat. Should we be waiting 30 years or more to assess the long term efficacy of these changes, or should we accept the argument that these changes are so minor as to not substantially alter the product/organism itself. And what effect do they have on indiginous species when released into the wild - when wheat species cross fertilise or insects pollinate different tomato crops?

My personal take, as a scientist with a career in genetics, is that given a choice I would avoid cloned meat. Not because I fear being turned into Frankenstein or developing a terrible disease, but because quite simply the long term consequences are unknown. If its impossible to tell whether meat is cloned or not in the foodchain the risk is not large enough to turn me vegitarian. But I do predict soon a revolution akin to the organic one where cattle are marked as cloned or genetically altered free and a premiuim placed on that tag. Quite apart from the fact we already have bef mountains and milk lakes - quite why we need to get more meat per animal or milk per cow is simply to increase farmers profits. Allowing rice to grow in drier conditions, or pesticide resistant crops in poorer countries does have benefits however. As with any technological advance the issue is not as black or white as either side would have you believe.

Is cloning dangerous, or playing God - not really, just speeding up evolution. Can it lead to ethically suspect outcomes and actions - absolutely - but that is a different discussion altogether from the scientific process of cloning.

Steve

 

[Digit]

You are absolutely correct Steve, my wording was very poor. What I should have said was that cloning guarantees the result, pretty much, once you have have a desirable trait.
If you take an animal with a desirable trait and cross it in the normal manner it could be several generations before that trait is 'fixed'.
Labour intensive, indeed, but look how long it took to produce the human genome when the programme started and how much quicker it is today.
In the future I can see the process being widely used to aid infertile couples. (if it hasn't already.)
People fear what is new, if the horse X donkey was accomplished by people like yourself there would, I suspect Steve, be the usual outcry.
Genetic engineering is another minefield of course. I see that a Japanese Beetle? is being released to combat Knot Weed, I wonder where that might end up.
As an ex development engineer I am well aware that you can only test for the possible outcomes that you can think of, it's the ones we miss that turn and bite us!

Roy.

 

[Maia28]

My personal take, as a scientist with a career in genetics, is that given a choice I would avoid cloned meat. Not because I fear being turned into Frankenstein or developing a terrible disease, but because quite simply the long term consequences are unknown. If its impossible to tell whether meat is cloned or not in the foodchain the risk is not large enough to turn me vegitarian. But I do predict soon a revolution akin to the organic one where cattle are marked as cloned or genetically altered free and a premiuim placed on that tag. Quite apart from the fact we already have bef mountains and milk lakes - quite why we need to get more meat per animal or milk per cow is simply to increase farmers profits. Allowing rice to grow in drier conditions, or pesticide resistant crops in poorer countries does have benefits however. As with any technological advance the issue is not as black or white as either side would have you believe.

Is cloning dangerous, or playing God - not really, just speeding up evolution. Can it lead to ethically suspect outcomes and actions - absolutely - but that is a different discussion altogether from the scientific process of cloning.

I thought this was an excellent response. I am involved in some areas of synthetic biology and it is notable that the funding bodies are now actively engaging ethicists and philosophers to consider these issues long before we see any "real" synthetic organisms. I also thought the example of growing rice in drier conditions was a good example to use as this is currently being pursued by a major bio-tech company. Interestingly, at a recent conference the idea of a photo-synthesising cow was proposed as a mechanism for increasing input-output yields. I guess it all depends on how far we want to go with this, but even apparently benign science needs a good regulatory framework to ensure public confidence based on sound long-term evidence.

Andy

 

[Digit]

ensure public confidence based on sound long-term evidence.

You two gentlemen should be able to correct me if I've got any of this wrong, but as I recall the Americans have been growing GM Lettuces and Tomatoes for something like 20 years. Again, IIRC the modification was to include a natural anti freeze from a species of fish to make the crops frost resistance.
So how long a term evidence is/will be sufficient for people? This seems to have worked in the above example but at the same time GM Soya seems suspect according to some reports but quite widely grown.

Roy.

 

[laird]

I thought that the bull was the offspring of a clone. (1/2 original clone), and the animals in question were the offspring of the bull, (1/4 clone).
By which time any genetic defaults would have shown up.
Anyone eaten/own any result of a selective breeding programme (which has, IMHO, a higher chance of genetic defects) - such as tomatoes, potatos, a non-mongrel dog, a horse, etc.etc.?

 

[StevieB]

In one of those strange quirks of timing, this report appeared on the BBC news this morning:

http://www.bbc.co.uk/news/science-environment-10859264

Once opened, its appears to be very difficult to close Pandora's box! On that depressing note, I am off for a weeks holiday

Steve

 

[Digit]

Well they were warned Steve, it was pretty predictable wasn't it?

Roy.