Wednesday, December 17, 2008

Cloning: saving the endangered species

By having exploited the earth’s resources in unbridled manner, for our needs (and greed), we have placed the numbers and very existence of several other life forms in jeopardy. We have aggrandized more land, used up more water, exploited more plants and animals, and produced more waste (much of which will not go away).

This has upset nature’s fragile equilibrium. One direct result of this is the endangerment of some life forms. A few examples are the Amazon rain forest, the panda, the great apes, cheetah, Asiatic lion and even the common Indian vulture. Some such as the dodo bird and the great American bison have been lost forever.
The folly

Fortunately, realization of the folly has dawned on us, even if late in the day. And several groups and international agencies are putting together contingency plans using new ideas of resurrection. Advances in biology in the last decades have come into use in this welcome move.

How does one repopulate an endangered species? By making more of them using the biological steps involved in reproduction. The method of in vitro fertilization (making test tube babies) is one such. Indeed, it has become so standard by now that it is hard to believe that it was only thirty years ago that Drs. Patrick Steptoe and Robert Edwards helped produce Louise Brown, the first test tube human baby.

With animals, we have gone one step ahead. In order to produce Louise, it was necessary to fuse her father’s genes (in his sperm) with her mother’s (in her egg) and place the fertilized egg back in the mother’s womb.

And when Louise was born, most of the cells in her body (barring some special ones) had the genetic contents of both her parents in the cell nucleus. In this sense, each such ‘somatic’ cell has all the genetic contents of the fertilized egg. It has the biology of the father and the mother in it.

Here is a thought experiment. Let us first take an unfertilized egg, remove its nuclear contents, and place in it the entire genetic material from a somatic cell.

Now let us place this egg in the womb of the ‘would-be’ mother and produce the baby. The baby so born will be genetically identical to the individual from whose cell we took the genes to place the empty egg.

The baby is thus the clone of that individual; and the latter is both the father and mother of the baby! The one who provided the egg is then the ‘surrogate’ mother.

This is the experiment that Dr Ian Wilmut of Edinburgh did in his lab when he produced Dolly the baby sheep.

In this case, the somatic cell came from a sheep (let us call her Holly), and the egg that was emptied came from another (Molly).

Holly’s nuclear material was placed in Molly’s donated egg, and this was placed in the womb of a surrogate (Polly?) and, in time, out came Dolly. She came out of a process that biologists call somatic cell nuclear transfer or SCNT.
An idea born

Here then is born the idea of cloning animals. What if we take carefully stored tissues and cells from animals long since extinct, or currently endangered, and do a Dolly on them? The devil is of course in the details — the way the tissue has been stored.

The genetic material in the tissue or cell should be intact, and not degraded and decomposed. Museum and archival samples are fine as long as they satisfy this condition.
Recent work

Recent work from the RIKEN Centre in Kobe, Japan shows that cloning is possible from cells of dead mice that had been frozen in a – 80 degree Centigrade deep freezer for 16 years!

Writing in PNAS (US) earlier this month, Teruhiko Wakayama and associates describe how they had taken material from the brain tissue of mice, did a SCNT into an emptied mouse egg and generated baby mice.

They also note that it was easiest to create clones from brain cells, presumably since brain tissue is rich in sugars, which protect cells from damage during freezing and thawing.

Close on the heels of this comes another cloning, this one on the endangered species called the Amami rabbit. Called a living fossil, these rabbits, once abundant in Japan, have been decimated by killer dogs and hunter men.

Cloning in this case was done using the ear cells of an Amami rabbit and transferring its nucleus into the emptied egg of an ordinary rabbit. The scientists expect the cloned Amami baby to arrive by mid-December.

Given these encouraging results, it should be possible to clone several endangered species, and the Hyderabad-based Laboratory for the Conservation of Endangered Species (LaCONES) will surely attempt to add this method as well, to its battery of techniques in assisted reproduction. They have the ability and the commitment to do so.

The technology raises important, and troubling, issues when we turn to humans. Would it be useful to clone and bring to life a Neanderthal? Or even a highly admired and revered homo sapiens?



1 comment:

A said...

Cloning as an alternative for other seemingly 'conservative' approaches for conservation can be advised only when the species can be resurrected by no other means like protection, habitat preservation, judiciary, outreach, etc.

The 2 reasons I can think of immediately are:

1. The lifespan of cloned animals has been not upto the mark. Their immunity is not as high and they fall prey to diseases and other maladies.

2. Since genetically a new-born is identical someone already present in the population, it's reducing the genetic diversity. In cases where resources are abundant for everyone, this would be ok. But when every animal in wild is battling for survival, compromising diversity for numbers can't be practised.

It is possible that you don't completely agree with the strategy explained in the articl, but then you should clearly mention that. Laymen will think cloning as an answer to a grave danger the humanity faces in form of loss of biodiversity. As I said before, it should be used only when a species has reached a point of no return.