W
hat is Biology Good For?
C
loning Endangered Species

(This assignment is optional. Read this essay and answer the questions at the bottom for 3 extra credit points. You may only turn in one per six weeks. The assignment is due one week before the end of the six weeks. It is not necessary to visit the links in the text unless you are interested in more information.)


Today, many breeds of livestock and wild animals are in danger of extinction. Because of the introduction of competitors, such as loss of natural habitat or poaching, the total number of living species is dropping at alarming rates. According to Peter Raven, the director of the Missouri Botanical Garden, species are becoming extinct at the rate of 100 per day or about 1 species every 15 minutes, due to the continual, daily habitat destruction for numerous species worldwide....thanks to humans...). If these present trends continue, at least 50% of all currently existing species will be either extinct or endangered by the year 2050 (Diamond, J.), equivalent to that of a mass extinction. [For an interesting persprctive on species extinction, read Henry Gee's article in Nature: "Back in 10 million years".]

Although these figures sound (and ARE) very bleak, a NEW type on conservation effort may save species from complete extinction. Zoos around the world have started programs in cloning endangered animals by nuclear transfer.

What is Somatic Cell Nuclear Transfer?

Simply stated, cloning by nuclear transfer requires merging DNA from a body (somatic) cell into an egg stripped of its own DNA. The composite is then implanted into a surrogate female for gestation. This process, first envisioned by Hans Spemann in 1938 and then succeeded by John Gurdon in 1970, continues to be used today and has given life to a variety of animals, including the the world's most famous sheep, Dolly.

Nuclear transfer requires specialized microsurgery tools and involves five basic steps:

1. Enucleation of the recipient egg (E = removal, nucleation = the nucleus)

Using an enucleation pipette, the nucleus, which
contains the eggs DNA, is removed from the egg. (left)

   

2. Transfer of the donor cell into the recipient egg

Again using the enucleation pipette, the donor cell is placed between the eggshell and egg membrane of the enucleated egg. (Above, right) Donor cells can be derived from a microscopic embryo, a fetus, or even from an adult animal, as was Dolly.

3. Fusion of the donor cell to the recipient egg.
The egg and donor are subjected to a low electrical charge, causing the membranes to fuse.

4. Culturing the resulting cloned embryo in the incubator

For 3 to 5 days, the embryo divides in a manner similar to that of a conventionally fertilized egg.

5. Transfer of the developing embryo into the reproductive tract of a surrogate mother of the same species

Depending of the species of the clone, implantation occurs between the 8 to 64-cell stage.

The surrogate mother will carry the clone to term and give birth as in a normal pregnancy. [Images: Lazaron BioTechnologies, Scientific American November 2000].

 

A New Twist to Nuclear Transfer

Just recently, new technological advances in cloning have been made. Scientists are now using a surrogate mother of a different species, thereby creating new hope for endangered and even extinct species. A recent attempt at this was "Noah," the clone of a rare wild ox, the guar.

Noah was created at Advanced Cell Technology (ACT) in Massachusetts by fusing skin cells from a guar that died in 1993 with cow eggs stripped of their nuclei. After a long gestation, Noah was born on January 8, 2001 and brief history was made. Unfortunately, less than two days later, Noah's life was cut short when he died from a common bacterial infection.

According to the scientists at ACT, Noah was normal, born "vigorous and bellowing," and now, the hunt is on to determine exactly how Noah contracted the infection. In the meantime, according to Philip Damiani, co-creator of Noah, programs using the same technique are underway to clone an extinct goat, the bucardo, and endangered wild cats, as well as more guars.

Why Clone Endangered Species?

Through these advances in cloning, we are give the chance to preserve and propagate endangered species that produce poorly in zoos until their habitats can be restored and they can be reintroduced to the wild. Also, the ability to recreate a species from a preserved cell line without a surrogate of the same specie is a clear pro of cloning. Most importantly, though, this advance allows the reintroduction of new genes back into the gene pool of a species with few remaining animals.

Unfortunately, despite the great potential cloning gives to endangered species, it cannot solve the problem at heart, habitat destruction and poaching.

References

The History of Cloning. 19 Feb 01.
Lazaron Technologies. Cloning pets and endangered speices 14 Feb 01.
New Scientist. Cloning Report: Rare clone dies. 19 Feb 01.
Scientific American. Cloning Noah's Ark. Nov 2000.

This Good For was researched and writted by IUPUI student Jennifer Manske for a Senior Research Project.

 

The text of this "What is Biology Good For" exercise is copyrighted under the name of Dr. Kathleen A. Marrs, 1999, 2000, 2001, 2003. There are no restrictions on its use by educators or by non-profit institutions as long as its content not modified, proper copyright acknowledgement is retained, and this statement is not removed.

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Extra Credit Questions: Please answer the following questions on a piece of paper and turn it into me.


1. What were the two animals used to create Noah?
2. Name an animal, other than the guar, that is
endangered.
3. There are other benefits to cloning besides saving endangered species. Name at least one.
4.Totally optional: Any idea why the company above might have chosen the name
Lazaron Technologies? (Does the name Lazarus - aside from the department store - ring a bell?)

 

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