Archive for June 2012
Last week, my pals and I spent a long weekend in Barcelona visiting the awesome Primavera Sound music festival. The rather nocturnal nature of the event (bands playing from 18.00 to 04.00) gave us plenty of time during the day to
sleep on the beach drink excessively visit some of the beautiful sights of one of Europe’s most vibrant cities.
So what did we see? Gaudí’s majestic Sagrada Família? The magnificent Camp Nou, home of FC Barcelona? Nope, we went to a science museum. Nerds: that’s how we roll.
CosmoCaixa, Barcelona’s science museum, is amazing and well worth checking out if you’ve a spare few hours on holiday. It has more hands-on exhibits than you can shake a stick at and comes complete with an indoor rainforest. Beat that, London Science Museum.
Poor old Vibrio vulnificus, it just can’t catch a break. This Gram-negative marine bacterium (and occasional human pathogen) is the first species found to be infected by both a virus and a predatory bacterium.
Let’s step back a moment and look at the smaller picture. Just like humans, bacteria are regularly infected by viruses. These viruses are known as bacteriophages, and they are the most abundant and diverse organisms on Earth: nobody really knows how many exist, but estimates suggest that there might be as many as 1031 on the planet (that’s more viruses than there are stars in the universe). Sometimes, after infection, the viruses integrate their genetic material into the host bacterial chromosome but remain dormant; other times, they force the bacteria to make multiple copies of themselves until the host cell can’t take any more and explodes.
Like bacteria, viruses have existed for millions of years, yet even after all this time we still don’t really know when or how they evolved. Viruses are grouped into families based on their genome, which can be either DNA or RNA.
Like all other organisms on Earth, viruses evolve, and they mix their genomes with each other in the environment to form new strains – which is why new flu strains appear each year. It was thought that viruses only mixed with others of the same family or with their close relatives, but researchers have discovered a new virus that seems to be a bit of a rule-breaker…
This virus, provisionally named BSL RDHV (Boiling Springs Lake RNA–DNA hybrid virus), is unusual because it seems to be a mix of both DNA and RNA viruses. A typical virus consists of genetic material (DNA or RNA) surrounded by a protein shell; the genetic material in this newly discovered virus is DNA, yet its shell contains a protein similar to those found in RNA viruses.
Through an unusual recombination event, the DNA virus seems to have picked up a gene from an RNA virus. Whereas DNA–DNA and RNA–RNA recombinations are well understood, we don’t understand how DNA–RNA recombinations work.
The new virus was discovered by researchers in the acidic Boiling Springs Lake at Lassen Volcanic National Park, USA. The researchers collected and analysed samples of DNA from the lake’s sediment, identifying the virus and its unusual RNA-derived gene. This technique, known as metagenomics, allows scientists to investigate genetic material from environmental microorganisms directly, instead of first growing them in the lab.
This new discovery is an important step in understanding virus evolution: it seems likely that RNA viruses evolutionarily preceded DNA viruses, so the authors speculate that the incorporation of RNA genes by DNA viruses might help to explain this branch of evolution.
Sruthi is a freelance science writer
Diemer, G., & Stedman, K. (2012). A novel virus genome discovered in an extreme environment suggests recombination between unrelated groups of RNA and DNA viruses Biology Direct, 7 (1) DOI: 10.1186/1745-6150-7-13