A prehistoric bee that lived at least 25 million years ago before drowning in a blob of sticky tree resin has provided scientists with proof that the ``dead'' can be brought back to life.
Inside the gut of the bee lived bacteria which helped the insect to digest its food. It is the spores of these bacteria that scientists have been able to revive in a series of startling experiments demonstrating that truth is stranger than fiction, even the fiction of Jurassic Park.
The stingless bee, belonging to a species that exists today, lived in what is now the Dominican Republic, in the West Indies, which is one of the richest sources of amber - fossilised tree resin - in the world.
Raul Cano and his student colleague, Monica Borucki, from the California Polytechnic State University, San Luis Obispo, operated on the amber-entombed insect in a laboratory where filtered air and washed utensils helped to prevent the insect from being contaminated with micro-organisms.
Dr Cano cracked open the amber to get at the bee and dissected the insect's gut to isolate the bacterial spores inside. He then transferred the spores, which are the microbe's means of transport from one bee to another, to a nutrient jelly.
Within a couple of weeks the spores had opened up to allow the bacteria inside to grow and flourish. Dr Cano was easily able to identify the bacteria as belonging to the same group of microbes that live in the gut of present- day bees, according to research published today in the journal Science.
How could he be sure he had extracted a genuinely ancient, indeed prehistoric bacteria? He had set up an elaborate system of control experiments to eliminate contamination but the strongest evidence came when he analysed the genetic material of the bacteria, which he found to be similar but not identical to present-day forms.
Dr Cano said the ancient bacteria also produced enzymes - molecules that speed up biological reactions - which are not produced by modern counterparts, a sign of the potential for discovering new drugs and biotechnology products from the prehistoric microbes.
He said that a total of about 1,500 microbes which produce spores, such as fungi and bacteria, have since been isolated from various specimens of fossilised amber from around the world, dating back as far as 130 million years. A second laboratory in California has replicated the research, he added.
Dr Cano said that he has revived a fungus from Lebanese amber that is dated to around 135 million years old. He has also revived bacteria from 35-million-year-old amber found near the Baltic Sea.
Spores of bacteria and fungi have long been known for their resilience, said Erika Hagelberg, head of the Ancient DNA Group at Cambridge University. ``They are the toughest things you can imagine. You can boil them for hours, irradiate them and still get residual activity.''
Dr Hagelberg, who has extracted ancient DNA from frozen mammoths, said she is ``cautiously optimistic'' that Dr Cano's research will not prove to be due to contamination with modern spores. ``I'd like to see whether it can be replicated,'' she said.
Andrew Ross, an amber expert at the Natural History Museum, in west London, said the preserving properties of fossilised tree resin is well documented. The ancient Greeks used amber to preserve wine and the ancient Egyptians used it to embalm corpses.
Insects and even small lizards trapped in amber suffer very little biological degradation. The amber prevents water and oxygen from getting at the insect and it also possesses antiseptic properties, Mr Ross said.
Phillipp Gerhardt, of Michigan State University and an expert in the survival of dormant microbes, said of Dr Cano's work: ``This is an exciting discovery, opening up a range of opportunities for studying microbial evolution. The results demonstrate beyond reasonable doubt that they have indeed succeeded in reviving a bacterium of ancient origin.''
Dr Cano stressed that if the research ever uncovers a microbe that resembles anything today that can infect humans then it will be destroyed straight away, ``no ifs or buts''.
Robin Steele, president of Ambergene, the company set up to exploit the research, said that work has now begun on trying to isolate useful compounds from the ancient microbes. ``Dr Cano's work enables us to tap into an unexplored universe of molecular diversity for the discovery of new drugs.''
Ambergene is working with a drugs company, Microcide Pharmaceuticals, of Mountain View, California, to identify new medicines.
Keith Bostain, the company's chief operating officer, said: ``Every ancient microbe tested to date exhibits antibacterial activity'', which indicates they possess chemicals that could act as new types of antibiotic drugs.
``Although we have not yet completed the elucidation of the chemical structure of any of the compounds, our initial data look very promising,'' Dr Bostain said.
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