Thursday, January 25, 2007

Camel fever!

Some of you might have read about the recent launch of the EDGE of Existence program in the UK. Designed to improve upon existing conservation strategies that only focus on the number of surviving individuals in a given species (as indicated by the species’ position on the IUCN's Red List), EDGE—which stands for “evolutionarily distinct & globally endangered”—uses a novel metric, basing the need for conservation action not only on a species' extinction status but also on its level of "evolutionary distinction," the amount of evolutionary history a species represents (determined by an examination of its family tree or phylogeny). The idea is that if an endangered species also happens to be one of the only species of its type left on the planet, a disproportionate amount of unique evolutionary history would be lost with its extinction, and conservation efforts should reflect that.

But what I really want to talk about is one of EDGE's ten focal species this year, the wild Bactrian camel (Camelus bactrianus ferus). These two-humped camels live in the fragile Gobi and Gashun Gobi deserts in northwest China and Southwest Mongolia, and it's estimated that only about 950 remain, making them "more endangered than the giant panda," according to the charity / non-profit organization The Wild Camel Protection Foundation. The foundation, whose patron is Jane Goodall, has recently established a captive wild bactrian camel breeding program in Mongolia to save—and study—these fascinating creatures, for it seems they might be harboring some pretty nifty secrets. First, they have been able to breed normally in an area of Gashun Gobi that has been host to extensive nuclear testing (according to an article first published in the London Independent, China has engineered more than 40 atmospheric explosions in the area in which the camels have lived); they have also evolved the ability to drink salt water slush instead of fresh water, something that domestic Bactrian camels cannot do. And there’s more. According to the foundation,
The immune system of a single humped, dromedary camel is beginning to yield amazing secrets. For example, an increased ability to resist certain types of diseases including diabetes through the consumption of camel milk. As it is possible that the single-humped camels descended from the double-humped camel, scientists have every reason to think that a detailed study of the immune system of the wild Bactrian camel will yield scientific discoveries which will be of benefit to the whole of mankind. For example, how is it that the wild Bactrian camels survived 43 atmospheric nuclear tests and are still breeding naturally without any recognisable deformities? How has the wild Bactrian camel managed to survive on salt water that the domestic Bactrian will not drink?
Getting deeper into the science, here is an excerpt from a 2000 2001 article in The Scientist:
Sabah Jassim, who is originally from Nottingham but now works in the UAE, at the Zayed Complex for Herbal Research and Traditional Medicine, is convinced that camels offer new hope for drug companies looking for treatments for hepatitis C and HIV. "There is something really marvelous in their immunoglobulin," he said. His center has carried out an overview of the existing research into the camel's immune system, going back to 1993, and published in the latest issue of the British Institute of Biology journal, Biologist. "The camel is unique, different from any animal in the world," he explained. "The only animal with anything like it is the shark."
And later on:
The camel's antibodies find it easier to penetrate enzyme—active sites than human antibodies. This, and the relatively small size and weight of the immunoglobulin molecule, offer enormous potential, as it could be used to tackle diseases such as salmonella, TB, hepatitis C, skin disease and HIV, argued Jassim. Camel immunoglobulin could be used to neutralize a viral enzyme, he suggested. And it appears to be able to fight off various pathogens.

Camel antibodies are also being studied by Serge Muyldermans, Senior Scientist at the Flemish Institute for Biotechnology in Brussels. He explained that, because a camel immunoglobulin molecule is much smaller than that of a human, it is able to penetrate the dense layer of protein coat around a virus or parasite more easily. His department has been developing ways of cloning immunoglobulin fragments from immunized camels to produce high yields of recombinant protein. The camel antibodies, he argued, have several advantages over conventional antibody fragments, and could be used as enzyme inhibitors, for diagnostic purposes, or even in treating tumors. "The idea is to link the camel antibody to enzymes which will bind to the tumor," he concluded.

The fact that camel antibodies are so light, proposed Jassim, makes them ideal for new clinical compounds. The antibodies have a molecular weight of 100 KDa, much lower than human antibodies, at 150 KDa, while the recombinant version weighs just 15 KDa. "I think pharmaceutical companies are not really aware of this," he said. But he thinks that camel antibodies are set to become big business in the future.
But that article was written back in 2001, so the obvious question is, what have these scientists learned since then? Sadly, I can't find a website for Jassim, and a PubMed search suggests he's published no camel-related papers since then. A look on Muyldermans' website reveals that although he is ostensibly still studying camel antibodies, he hasn't published any related studies since 2003, when he published in Nature that a particular camel antibody fragment inhibits the aggregation of a protein variant of human lysozyme that is involved in the production of amyloid fibrils—the signature of diseases like Alzheimer's and Parkinson's. The paper says that "the binding of the antibody fragment achieves its effect by restoring the structural cooperativity characteristic of the wild-type protein...Reducing the ability of an amyloidogenic protein to form partly unfolded species can be an effective method of preventing its aggregation, suggesting approaches to the rational design of therapeutic agents directed against protein deposition diseases."

Sounds exciting, and I'll look forward to hearing more about the medicinal potential of Bactrian camel immune proteins, but I'm not holding my breath either. These substances have barely been studied in the lab, let alone developed into potential therapeutics, where they'd have to undergo further scrutiny in animal and clinical trials. You can’t predict much from research at this stage, but it's certainly fascinating to follow, so I'll continue to do so.

Assuming these camels don't go extinct, of course.

2 Comments:

Anonymous free ps3 said...

Thanks for the nice post!

6:21 AM  
Blogger Amenon said...

Very interesting. Strangely Ablynx seem to be the only ones following this up. They just recently entered a research partnership with funding from Boehringer-Ingelheim - so it seems some people have faith in the potential of nanobodies.

Your article highlights one aspect of the importance of biodiversity to humans.

2:45 PM  

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