Friday, November 18, 2005

Sugar and spice and everything nice, of course.

The New York Times has many uses, one of which affords me a nice scratchy crumply surface for cleaning my paws. While visiting the litter-box this morning, I read an interesting story entitled With Genetic Mapping, Cats' Mysteries Will Be Unraveled. The author purports that a purebred cat will offer up secrets of genetics -- specifically, the domestic cat genome -- and will allow the pet-food monopoly to make even more vile food for most cats to eat. Luckily for me, I get freshly-steamed broccoli and roasted chicken for diner. There is truth in the article: "The domestic cat is the only one of the 37 species in its family that is not either threatened or endangered. Yet despite their rapidly shrinking territory, and their limited genetic diversity within species, wild cats endure on every continent except Australia and Antarctica, at the top of the food chain wherever they live."

February 15, 2005
With Genetic Mapping, Cats' Mysteries Will Be Unraveled

Genetically speaking, every dog has already had its day. In 2003, a standard poodle named Shadow became the first canine to have his genome mapped, and in 2004 a boxer, Tasha, became the second.

Now scientists are turning their attention to the genome of the domestic cat, and it is Cinnamon's turn to donate a blood sample.

Cinnamon is not just any cat. She comes from a carefully bred colony at the University of Missouri, and her lineage can be traced back for decades.

Scientists therefore know exactly what they are getting when they look at her DNA.

Researchers hope to have the cat genome mapped by the end of the year - perhaps as soon as this summer - and when the job is done, humans will be the ones to benefit.

Americans own (or serve) more than 60 million cats, spend over $4 billion a year on cat food and are so dedicated to feline health care that their veterinarians have identified more than 250 genetic diseases and hundreds of infectious agents that afflict them.

But the genome will usher in a world of knowledge with immediate practical application, not only for veterinarians and cat owners, but for geneticists, zoologists and conservationists as well.

When the National Human Genome Research Institute, part of the National Institutes of Health, chose the cat as one of the select group of species to have their genomes mapped, it conferred no small honor. It will cost $5.5 million to do the job, said a spokesman for the health institutes, and though the project will produce a map that is far less detailed than that of the human genome, scientists firmly believe it is worth every penny.

The sequencing is being carried out under contract with Agencourt Bioscience Corporation, a biotechnology firm in Beverly, Mass., which was started five years ago by scientists originally involved in the Human Genome Project.

The cat genome is large, and even though automated equipment is used at every step, sequencing it is labor intensive; more than 100 people are involved in one way or another in the project.

The raw material - Cinnamon's DNA - is delivered to Agencourt by the N.I.H. Then the work begins, essentially a process of chopping up the DNA into tiny usable pieces in a process called library construction, and then putting it all back together to create the map. Producing a usable first draft sequence takes about nine months.

The Cat Genome Project was announced along with plans to sequence the genomes of eight other mammals: the elephant, the orangutan, the shrew, the hedgehog, the guinea pig, the tenrec, the armadillo and the rabbit.

Each new genome map adds something to the understanding of the human genome, but the cat was chosen, among other reasons, for its importance as a medical model in studying human disease.

"The genes on the cat chromosome and the human chromosome correspond to each other like two strings of beads made of different colors," said Dr. Stephen J. O'Brien, chief of the Laboratory of Genomic Diversity of the National Cancer Institute, adding that cats have "the same genes, one after another, strung together across every chromosome."

This resemblance means that many of the cat's genetic diseases are inherited exactly the same way as genetic illnesses in humans. Diabetes, hemophilia and lupus, for example, have precise genetic homologues in cats.

Cat retroviruses, like those that cause feline leukemia and feline sarcoma, although slightly different in their gene structure from the human versions, produce lesions that look almost identical to human cancers. Perhaps even more significant, feline immunodeficiency virus, or F.I.V., resembles H.I.V. so closely that it follows the same progression that, untreated, leads to the wasting syndrome of AIDS in humans. It is the only known naturally occurring AIDS syndrome in any nonhuman species, and provides a perfect model for studying the progression of the disease.

Cats also get feline versions of many other human infectious diseases, including rotavirus, poxvirus, herpes, Q-fever, chlamydiosis and dozens more. On top of that, they are resistant to anthrax infection, a fact of considerable interest to scientists. Once the genome is mapped, said Dr. O'Brien, "research on feline stem cells will blossom, along with gene therapy applications."

Zoologists and wildlife managers are just as eager as medical researchers to start using the completed cat genome.

The domestic cat is the only one of the 37 species in its family that is not either threatened or endangered. Yet despite their rapidly shrinking territory, and their limited genetic diversity within species, wild cats endure on every continent except Australia and Antarctica, at the top of the food chain wherever they live.

"The free-ranging species are survivors," Dr. O'Brien said. "Cheetahs, for example, get infected with F.I.V., but they don't get sick," though no one knows why.

On the other hand, wild cats can become infected for reasons that are just as mysterious. This happened in 1994 when the canine distemper virus, which normally infects only dogs, suddenly jumped to lions. Wildlife managers watched, appalled, as the virus swept through the population, killing one-third of the lions in the Serengeti ecosystem in only nine months.

Zoologists want to know what explains these evolved genetic defenses and susceptibilities. The genomes of the domestic cat and its wild relatives are almost identical, and the genetic information developed for the domestic cat will apply widely to all the species in its genus.

"The full genome," Dr. O'Brien said, "will empower people with tools to discover innate disease defenses, recognize pathogens and other threats and assess the present status and future of these species."

Cats were probably first domesticated about 6,000 years ago, making them much newer guests in the human household than dogs or barnyard animals, which have lived with humans for almost twice as long. Yet they are the domestic animal closest to our hearts in more ways than one.

"At least from a genomic perspective," Dr. O'Brien said, "cats share a striking ancient affinity with humankind."


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