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Invasion of the ocean body snatchers

14 August 2003

A paper in Nature today (14 August) reveals that certain ocean viruses invade the cells of cyanobacteria (known as blue-green algae) and use the energy the cells produce through photosynthesis for their own purposes.

Researchers at the University of Warwick, led by Professor Nick Mann, have shown that when the viruses infect the bacteria they inject their genetic material into their host, a transfer that may be temporarily advantageous to the host.

Part of the injected DNA codes for a protein which repairs the damage done to cells by too much light from the sun. Normally, the bacterial cells shut down when this photoinhibition occurs and when their own repair mechanisms cannot keep up with the damage. The viruses thus take responsibility for the repairs, and by keeping the cells alive, use the energy provided via photosynthesis to replicate themselves.

Viruses in general and bacteriophages in particular (the sorts of virus that infect bacteria) are abundant in the oceans. The bacteriophage that infects the bacterium, Synechococcus, in the study is known as S-PM2.

Tiny cyanobacteria (around a micron – one millionth of a meter – in diameter) are responsible in the open ocean for 30 – 90% of photosynthesis. Thus, the infecting viruses may be having major effects on the ecology and chemistry of the marine environment.

Professor Mann said, "Our results mean that a proportion of photosynthesis in the ocean might be mediated by viruses. This is an intriguing idea when you consider that roughly 45% of the oxygen we breathe is produced globally by the oceans."

He added, "Whilst there may not be any immediate practical implications, it also shows the ecological importance of viruses for transferring genes horizontally to other species."

Professor Mann's studies on gene transfers between viruses and bacteria are part of a major initiative on microbial biodiversity, supported by the Natural Environment Research Council.

Further information

NERC Press Office
Natural Environment Research Council
Polaris House, North Star Avenue
Swindon, SN2 1EU
Tel: 01793 411561
Mob: 07917 557215

Professor Nick Mann
Tel: 024 7652 3526

Jenny Murray
University of Warwick Press Officer
Tel: 024 7657 4255
Mob: 07876 2177

Notes

1. The full paper, 'Is there a viral input to oceanic photosynthesis?' by Nicholas H. Mann, Annabel Cook, Andrew Millard, Shaun Bailey & Martha Clokie, University of Warwick, is published in Nature, 14 August 2003.

2. NERC's programme on microbial biodiversity brings together the expertise of more than 20 UK research groups, covering the ecology, molecular biology and biotechnological potential of marine and freshwater microbes.

3. Blue-green algae are abundant in both freshwater and the sea. But they are actually bacteria, not algae, and they also come in other colours – the Red Sea getting its name from the blooms of a red-brown species, Trichodesmium, that occur there. In the late 1970s through to the 1980s, many new groups of such bacteria were discovered, including Synechococcus and Prochlorococcus, used in this study.

4. The viruses may have originally acquired the genes they use in repairing the photosynthesis mechanism from the bacteria themselves.

Press release: 16/03

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