Saturday 16 January 2010

DNA of Pest-Killing Wasps Could Unlock Other Secrets

(Jan. 15) -- The science community is abuzz over the news that the entire genetic makeup of a highly valuable wasp has been determined via DNA sequencing.

Nasonia is the name given to three different species of pinhead-sized, parasitic wasps that act as a kind of natural pesticide: They sting -- and lay their eggs inside of -- only certain, crop-destroying pests, greatly reducing the need for artificial chemical treatments.

Such biological pest control has been practiced for thousands of years (the ancient Chinese used beneficial ants to protect their citrus trees), but modern science could take the practice to a new level. By understanding exactly which genes tell the Nasonia to attack the pests they do, scientists hope to heighten the wasps' pest-killing proficiency, breed them in mass, and synthesize their venom. Someday their DNA could even be used to develop drugs for combating human diseases.

Nasonia wasps are interesting to scientists on another level: Their species have been around for only several hundred thousand years, making them one of Earth's younger insect groups. During that time, Nasonia picked up genes from pox viruses and other bacteria. One of the next projects for researchers is to find out what purpose these additional genes serve for the wasp.

Three researchers from three universities were responsible for the sequencing success, which they Edward Winstead, former managing editor of The Genome News Network, reports that the 1000th genome was recently sequenced, to much celebration. Some of the more interesting among this number include:

Anopheles gambiae
. This species of mosquito is responsible for the rampant spread of malaria in Africa and the 300 million to 500 million infections around the world annually. Unfortunately, this deadly bug has developed resistance to many pesticides, so sequencing of its genome is especially critical for developing effective methods of killing it or eliminating its disease-carrying properties. A working draft of the sequence was published in Science in 2004.

Canis familiaris. "Man's best friend" has also been one of his most loyal and helpful partners in many areas of scientific research (see Laika), and the field of genomics is no exception. The genomes of a standard poodle and a boxer were sequenced in 2003. The Broad Institute, a prominent genetic research center, notes: "The unique breeding history of dogs, with their extraordinary behavioral and physical diversity, offers the opportunity to find important genes underlying diseases shared between dogs and humans, such as cancer, diabetes and epilepsy."

Deinococcus radiodurans. Also known as the "Hulk of Microorganisms." Listed in Guinness World Records as the toughest bacterium on earth, D. radiodurans is resistant to extreme cold, vacuums, acid and levels of radiation that would destroy 99 percent of earth's other lifeforms. Radiation blasts shatter the bacteria's DNA, but it can reassemble itself. Scientists hope to use this bacteria to help colonize Mars and travel into deep space, protecting astronauts from cosmic radiation. The genome sequence of the bacteria, discovered in 1956 in a can of spoiled meat, was completed in 1999.

Tetraodon nigroviridis: The Green Spotted Puffer fish. Native to Southeast Asia, this fish is bred by humans to keep as a pet and used for sushi in some restaurants, although it can be poisonously fatal thanks to a "potent neurotoxin." What makes this animal more compelling to study than other fish is the fact that it contains the "smallest genome known to date in the vertebrates," sequenced in 2002. That is: Of all animals that have a backbone, the puffer has the least amount of DNA to explain its development, even though it contains many of the same genes as humans. Scientists have looked at them to see how evolution differs between mammals and fish.

And finally, Homo sapiens. A.k.a., well, us. The much-heralded Human Genome Project was actually two efforts to sequence our complete DNA profile. The collective sequencing effort took over 13 years, and the first drafts were completed in 2000. An updated, finalized version was released in 2003. The National Human Genome Research Institute described the milestone this way:
Having the essentially complete sequence of the human genome is similar to having all the pages of a manual needed to make the human body. The challenge to researchers and scientists now is to determine how to read the contents of all these pages and then understand how the parts work together and to discover the genetic basis for health and the pathology of human disease. In this respect, genome-based research will eventually enable medical science to develop highly effective diagnostic tools, to better understand the health needs of people based on their individual genetic make-ups, and to design new and highly effective treatments for disease.
In other words, for as far as gene science has come, it's only the beginning of what scientists hope to accomplish. But sequencing Nasonia is another big step forward.

http://www.sphere.com/science/article/dna-of-pest-killing-wasp-nasonia-could-unlock-other-genetic-secrets/19317696
(Submitted by T. Peter Park)

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