Pollution endangers Rare Chinese white dolphin: DNA bank

An endangered Chinese white dolphin (Sousa chinensis chinensis) swims off the coast of Hong Kong in August 2011.

A Hong Kong conservation group has set up a DNA bank for the rare Chinese white dolphin, also known as the pink dolphin, in a bid to save the mammals facing a sharp population decline.

There are about 2,500 Chinese white dolphins in the busy insutrialised Pearl River Delta region, the body of water between Macau and Hong Kong, with the majority of the mammals in Chinese waters and the rest in Hong Kong.

But experts say their number has dropped significantly in the past few years due to overfishing, an increase in maritime traffic, water pollution, habitat loss and coastal development.

In a bid to save the dwindling population, the Ocean Park Conservation Foundation Hong Kong said it had joined hands with a Chinese university to set up a DNA bank, which will also spearhead a genetic research project.

"We hope to offer the scientific community a standardised genetic analysis platform to assess the sustainability of Chinese white dolphin populations," Judy Chen, the foundation chairwoman said in a statement.

"The collected data will provide important reference to governments in the region for developing critical strategies of Chinese white dolphin conservation," she added.

The biological samples of these dolphins will be sent to the DNA bank to investigate the environmental impacts on the mammal, the statement said.

The Chinese white dolphins, a sub-species of the Indo-Pacific humpback dolphins, are unique for their pink skin. They are listed as "near threatened" by the International Union for Conservation of Nature.

The mammal was the official mascot at the handover ceremony when the former British colony returned to Chinese rule in 1997, while dolphin watching is a favourite tourist attraction in Hong Kong.

Its population in Hong Kong has dropped from an estimated 158 in 2003 to only 75 in 2010, according to the Hong Kong Dolphin Conservation Society.

The Black Death: DNA extracts of the plague bug Yersinia pestis

These are skeletons of victims of the Black Death from East Smithfield, London.

Scientists have extracted fragments of bubonic plague DNA from their teeth.

Fragments of 700-year-old DNA from the bug responsible for the Black Death have been pulled from the teeth of four plague victims buried in east London.

Scientists used the degraded strands to reconstruct the entire genetic code of the deadly bacterium. It is the first time experts have succeeded in drafting the genome of an ancient pathogen, or disease-causing agent.

The researchers found that a specific strain of the plague bug Yersinia pestis caused the pandemic that killed 100 million Europeans - between 30% and 50% of the total population - in just five years between 1347 and 1351.

Picture: Museum of London Archaeology /PA

"This is the first time a human pathogen more than a century old has ever been fully sequenced," says Johannes Krause at the University of Tübingen, Germany. 

The teams used DNA from modern Yersinia in an array that bound to similar DNA in victims' teeth. That DNA carried telltale chemical changes showing it was indeed ancient plague. Differences reported earlier between it and modern Yersinia were not confirmed.

The sequence also shows the ancient bacteria started infecting humans at the right time, between 1240 and 1340, just before the disease exploded (Nature, DOI: 10.1038/nature10549).

Yersinia has for some time been the prime suspect because some of its symptoms are similar to the Black Death. But questions were raised because modern Yersinia is a slow-spreading, rat-borne disease that is very different from the Black Death. 

Its DNA doesn't explain why. "There are almost no genetic differences between the ancient and modern Yersinia," says Krause.

He speculates that the Black Death behaved differently from modern Yersinia infection due to Europeans' total lack of previous exposure. 

Another possibility is co-infection with other pathogens, a so-called syndemic. The team hopes to learn more about the evolution of human disease by probing plague pits and other ancient samples for different pathogens.

DNA Evidence Can be Fabricated: Proof

Scientists in Israel have demonstrated that it is possible to fabricate DNA evidence, undermining the credibility of what has been considered the gold standard of proof in criminal cases.

The scientists fabricated blood and saliva samples containing DNA from a person other than the donor of the blood and saliva. They also showed that if they had access to a DNA profile in a database, they could construct a sample of DNA to match that profile without obtaining any tissue from that person.

“You can just engineer a crime scene,” said Dan Frumkin, lead author of the paper, which has been published online by the journal Forensic Science International: Genetics. “Any biology undergraduate could perform this.”

Dr. Frumkin is a founder of Nucleix, a company based in Tel Aviv that has developed a test to distinguish real DNA samples from fake ones that it hopes to sell to forensics laboratories.

The planting of fabricated DNA evidence at a crime scene is only one implication of the findings. A potential invasion of personal privacy is another.

Using some of the same techniques, it may be possible to scavenge anyone’s DNA from a discarded drinking cup or cigarette butt and turn it into a saliva sample that could be submitted to a genetic testing company that measures ancestry or the risk of getting various diseases.

Celebrities might have to fear “genetic paparazzi,” said Gail H. Javitt of the Genetics and Public Policy Center at Johns Hopkins University.

Tania Simoncelli, science adviser to the American Civil Liberties Union, said the findings were worrisome.