MadSci Network: Molecular Biology

Re: Is it possible for me to clone a small animal (If so, please tell me how)?

Date: Mon Apr 9 15:53:39 2001
Posted By: Christopher Carlson, Senior Fellow, Dept. of Molecular Biotechnology
Area of science: Molecular Biology
ID: 986512315.Mb

Hi Jenna,

You pose an interesting question. The challenge is whether cloning is feasible in a high school lab at present. In a nutshell, it would probably be extremely difficult, if not downright impossible to perform the type of cloning experiments you see in the news. Having said that, please read on for why, as well as some suggestions for related subjects that should be within reach.

It's still quite challenging to clone mammals via nuclear transfer even in the research university setting, so I'd venture to say that it would be impossible without the direct assistance of a research group who are already very good at it. The micromanipulator needles required to extract/insert the nuclei are very expensive, and developing the necessary skills to use them effectively takes years. As a consequence, most groups of this type have one person who is very, very good at the process, and this person handles all nuclear transfers for their group. Even with a professional doing the transfers, it takes tens to thousands of attempts to produce even one successful clone.

I'm not really sure about flies, but there are several types of experiment which might be feasible in amphibians. Historically, several categories of nuclear transfer experiment have been performed. Nuclear transfer in frogs is a lot easier because the egg cell is so much bigger. As far back as the 50's Briggs and King performed nuclear transfer experiments in the leopard frog, and in the 60's Gurdon expanded on this work in Xenopus laevis. In these experiments unfertilized eggs are blasted with UV radiation to demolish the DNA in the nucleus, and then nuclei from differentiated cells in tadpoles are injected into the UV'ed egg, producing clones. I wouldn't recommend these experiments to a high school lab for two reasons: the levels of UV required are actually rather dangerous, and the success rates for even experienced injectors are only on the order of 1-2% of all microinjected eggs. For details see the Scientific American article cited below.

There is a relatively low-tech way to produce "clones" of frogs: the frog egg is so big that in many species you can see the cell divisions with the naked eye. After the first few divisions (I can't really remember how many, but certainly up to the 4 cell stage) it is possible to actually cut apart the daughter cells and they will proceed through development relatively normally. The divided eggs will thus produce identical twins (clones). It would be interesting to see whether your results match those of Cooke and Webber (see refs). I would predict a much greater chance of success with this experiment than with a nuclear injection experiment, and would suggest it as a prelude to nuclear transfer.

In either case, I expect that the hardest part for you will be simply getting eggs from your frog. In frog labs they usually use hormonal injections to prime the frogs to produce eggs. If you had access to a frog lab at a local university I think you could probably ask for help in procuring eggs. If such access is lacking, then I'd suggest one of two routes: either visit the local pet store and ask them which frogs are the easiest to breed, or order some from a lab supply company. I am sorry that I'm not actually a frog person: the best advice I can give is that "Frogs, Toads, and Treefrogs: Everything About Selection, Care, Nutrition, Breeding, and Behavior" by Bartlett and Bartlett looks useful (and cheap), and I know you can order frogs and get some useful info on them at the Carolina Biological Supply Co.

Good luck,

Chris Carlson

Frog nuclear transplantation refs:
Peter Russell, Genetics, 2d edition, p. 669: Nuclear Transplantation Experiments J. B. Gurdon, Transplanted nuclei and cell differentiation, Scientific American 1968, v 219 pp. 24-35

Embryo Division refs:
J. Cooke and J. A. Webber: Dynamics of the control of body pattern in the development of Xenopus laevis, Journal of Embryology and Experimental Morphology, v 88, pp. 113-33. (for this one you'll need a university library)

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