ANOTHER LIFE:THE FIRST yacht of summer hovered off the mouth of Killary Harbour as if to distil, in a single gleaming triangle, the morning sunshine flooding down the fiord. A sharp east wind held the Atlantic flat, blue and infinite beyond, writes MICHAEL VINEY
It was a day to imagine the surge of growth in the sea – the exponential blooming of phytoplankton’s microscopic cells, plant food basic to marine life. But the ocean is still revealing organisms – nanoplankton, picoplankton – with smallness and number that go far beyond imagining.
Cyanobacteria may carry out half the ocean’s photosynthesis. Archaea, those most ancient of bacteria, swarm around the vents of the deepest, darkest Atlantic, making food of the Earth’s seep of minerals. And along with the millions of bacteria in any thimble of seawater could be 10 million viruses, even smaller again. Like the rest of the planet, the ocean is permeated with these invisible, powerful microbes.
A virus is a packet of genes in an envelope of proteins, looking for a cell to invade and parasitise, in order to spread. Most have only a few genes – HIV has only nine and the new swine flu, H1N1, perhaps eight genetic segments in its unstable mix. In the ocean, all but a few of the millions of viruses are still anonymous – part of the great volume of sea life that has yet to be explored. At one scale, they infect marine animals; at another, they contribute to the death of bacteria and plant plankton, releasing minerals such as carbon for recycling.
Some of the ocean viruses are giants, comparatively speaking.
One decoded by researchers at the Plymouth Marine Laboratory has a remarkable 472 genes. It matters because it infects a plankton species that helps to control our climate. Emiliana huxleyi, a chalky-shelled species that can turn the Atlantic milky with its blooms, soaks up billions of tonnes of carbon from the atmosphere and then, in the release of a gas, dimethylsulphide, or DMS, provides particles that helps the clouds to form.
Exactly how the virus acts on Emilianais still under study. But among its genes is a cluster that produce ceramide, a "death mechanism" that prolongs the life of a cell and then kills it at will. By delaying a cell's death, the virus can use it as a factory in which to replicate itself.
Ceramide, more commonly seen in animal and plant cells, has its attractions for human use, as a key component of anti-wrinkle, anti-ageing skin creams now on the counters of chemists’ shops. Its discovery in a marine virus may lead to other medications with more profound impacts on human disease.
Now that genes can be plucked out from nature at human will, for all manner of recombination, even a virus’s implacably purposeless drive to replicate and spread can be diverted for human benefit.
To ask what viruses are for leads us straight into the existential arena commanded by Richard Dawkins. It is tempting (I, at least, am tempted) to see their periodic plagues as one of Gaia’s attempts to remedy the human overpopulation of the planet: a feedback mechanism made inevitable by human progress in putting off natural death. The use of ceramide in anti-ageing creams thus becomes doubly ironic.
Dawkins, of course, insists on the futility of attributing purpose to nature, which just is. “Viruses,” he writes, “are coded programme instructions written in DNA language, and they are for the good of the instructions themselves. The instructions say ‘Copy Me and Spread Me Around’.” Viruses spread in a similar manner to those devised by global computer vandals and even use a similar language to engineer their effects.
In the process, however, they evolve by mutation – mistakes in their copying that are sifted by natural selection to survive and serve the further dispersal.
“Aids,” as British geneticist Steve Jones has put it, “is Darwinism unadorned.” Potentially fatal biological viruses can seem in no hurry to kill, so long as its victims are busily infecting plenty of others.
As cross-infection slows, selection works to favour variants that keep the bearers alive for long enough to pass the virus on. Any apparently constructive side-effects of viral action, such as keeping up the carbon supply from phytoplankton corpses, must be reckoned as incidental to their existential programme.
Ocean bacteria have already become the new raw material of industrial biotechnology and genetic engineering. Craig Venter, the American who mobilised private money to sequence the human genome, sampled the Sargasso Sea to find more than a million new genes from some 1,800 species of microbe previously unknown to science. Nearer home, bacteria figure prominently in the “biodiscovery” programme of the Marine Institute on Galway Bay, and researchers at NUI Cork are extracting DNA from bacteria sucked in by sponges in the hope of finding “interesting” molecules.
The oceans may be infinitely huge, but among their most profitable secrets may be those yielded by the infinitely small.
Eye on Nature
I had an extraordinary encounter with a common dolphin in Derrynane Harbour. It was behaving strangely, drifting idly in shallow water, then writhing. I waded in and made sure he was aware of my presence, and after a bit he came up to me, stopping at my feet. I reached out to touch him, first his fin, then running my hand along his back and flank. He rolled over. I thought for a moment he was dead. I rang a friend, who said that sometimes they have bacteria in their skin and come in to roll in the sand, for a good scratch. After a bit he moved in beside a rock in the harbour. I climbed on the rock and sat there beside him. Next he tried to climb out of the water, and went into minor convulsions. He had cut his beak and his eye on the rock. The tide was coming in rapidly, so I had to leave and reported it to a ranger. Next day I found the dolphin exactly where I had left him, dead upon the rock. It was very sad, but exhilarating to encounter such a wild animal and bear witness to its need for the company of another in a time of stress.
Roy Tangney, Cork
A thrush has built a nest and laid five eggs in it on the window sill of one of our upstairs rooms.
Ned Cusack, Moycullen, Co Galway
Michael Viney welcomes observations at Thallabawn, Carrowniskey PO, Westport, Co Mayo. E-mail: viney@anu.ie. Include a postal address.