What makes nature's clocks tick?

By Aussiegirl

Now as I was young and easy under the apple boughs
About the lilting house and happy as the grass was green,
The night above the dingle starry,
Time let me hail and climb
Golden in the heydays of his eyes,
And honoured among wagons I was prince of the apple towns
And once below a time I lordly had the trees and leaves
Trail with daisies and barley
Down the rivers of the windfall light.

And as I was green and carefree, famous among the barns
About the happy yard and singing as the farm was home,
In the sun that is young once only,
Time let me play and be
Golden in the mercy of his means,
And green and golden I was huntsman and herdsman, the calves
Sang to my horn, the foxes on the hills barked clear and cold,
And the sabbath rang slowly
In the pebbles of the holy streams.

All the sun long it was running, it was lovely, the hay
Fields high as the house, the tunes from the chimneys, it was air
And playing, lovely and watery
And fire green as grass.
And nightly under the simple stars
As I rode to sleep the owls were bearing the farm away,
All the moon long I heard, blessed among stables, the nightjars
Flying with the ricks, and the horses
Flashing into the dark.

And then to awake, and the farm, like a wanderer white
With the dew, come back, the cock on his shoulder: it was all
Shining, it was Adam and maiden,
The sky gathered again
And the sun grew round that very day.
So it must have been after the birth of the simple light
In the first, spinning place, the spellbound horses walking warm
Out of the whinnying green stable
On to the fields of praise.

And honoured among foxes and pheasants by the gay house
Under the new made clouds and happy as the heart was long,
In the sun born over and over,
I ran my heedless ways,
My wishes raced through the house high hay
And nothing I cared, at my sky blue trades, that time allows
In all his tuneful turning so few and such morning songs
Before the children green and golden
Follow him out of grace.

Nothing I cared, in the lamb white days, that time would take me
Up to the swallow thronged loft by the shadow of my hand,
In the moon that is always rising,
Nor that riding to sleep
I should hear him fly with the high fields
And wake to the farm forever fled from the childless land.
Oh as I was young and easy in the mercy of his means,
Time held me green and dying
Though I sang in my chains like the sea.

This beautiful paean to the joyfulness of life is Fern Hill, by Dylan Thomas. It's not all that relevant to this article, which discusses the latest research on biological clocks -- but then clocks measure time, and this marvelous poem is about time, and one of my favorites -- so I think it only fitting to blend the beauty of science with the beauty of poetry.

Telegraph Connected What makes nature's clocks tick?

What makes nature's clocks tick?
(Filed: 15/08/2006)

European scientists are hoping to discover the secrets of biological timepieces, reports Roger Highfield.

Read any brief history of time and there is no doubt who was the greatest clock-maker of all. More than two centuries ago, John Harrison blended lignum vitae wood, brass, bronze and steel components to compensate for changes in temperature and pressure and so produce chronometers of remarkable accuracy.

But, as ever, nature got there first. She invented clocks billions of years ago, the descendants of which still tick in the cells of your body. To cope with the changing seasons, living things came up with the equivalent of Harrison's gridiron mechanism, consisting of alternating brass and iron rods assembled so that expansion and contraction rates cancelled each other as the chronometer moved from the Tropics to colder climes.

Now Harrison's mission is to be continued by the £8 million European project, Euclock, involving scientists at 29 sites in 11 countries. The project has been launched to find the secrets of nature's timepieces, including a novel project to recreate one. This synthetic biological timepiece will help them to lay bare the many secrets of biological clocks, which are ubiquitous - look at the way flowers open and close, the beating of the heart and the remarkable emergence of periodic cicadas every 17 years. [....]

Although we talk of the "body clock", there is no single chronometer in the body, but a superclock: timepieces probably reside in every one of our cells. Being a little inaccurate (left to their own devices, days would last longer than 24 hours) they are reset by various cues, the most important of all being light picked up by a tiny region of the brain called the SCN, at the junction of nerves from the eyes. It is not clear how the SCN synchronises all the peripheral clocks. Perhaps, by the action of hormones such as melatonin, the SCN ensures they all show the same "body time".

For the European project, Prof Andrew Millar, of the University of Edinburgh's school of biological sciences, will seek inspiration from the biological clocks in our cells, which consist of interlinked cycles of waxing and waning proteins, where each one affects another protein cog. Like so much basic machinery of life, these proteins are similar to those in mice, fruit flies and a host of other creatures.

The new project aims to see if we really understand these clocks and how they are entrained, which is increasingly important for the health of our 24-hour society. Although great strides have been made in finding clock genes, we still have much to do to work out how they act together to make a rhythm. This was underlined a few weeks ago by a study by Daniel Forger, at the University of Michigan, who found a faulty clock protein worked in the opposite way to that thought previously. [....]

Did clocks evolve to harness the metabolisms of living things to the cycle of day and night to make them use energy most efficiently? Or was it more important for them to evolve to help to hide the delicate process of reading genes and copying DNA at night, away from the disruptive effects of ultraviolet light?

The answers may lie in a dish of yeast cells that glow green - like clockwork.