- Humans find a resource in the extremely short lifespan of the annual fish Nothobranchius furzeri, a native of Zimbabwean temporary bodies of water. The short-liver could prove useful in laboratories worldwide.
Alessandro Cellerino and Stefano Valdesalici of the Pisa-based Italian Istituto di Neuroscienze have published a new study in the 'Biology Letters' of the Royal Society in London, describing the advantages of a short life span of the Zimbabwean fish species - for human science.
The small fish Nothobranchius furzeri inhabits a harsh environ; the short-lived water bodies that fill up temporarily during the rainy season. Within a few weeks, the fish has to do what other fishes can spend a real lifetime to accomplish: hatch, grow into a fish, graze, reproduce, lay eggs and die.
The species only to be found in Zimbabwe goes through this lifespan in a matter of less than twelve weeks, Mr Cellerino and Mr Valdesalici found out in laboratory experiments.
The species is a member of a group of annual species found in temporary bodies of water whose life expectancy in the wild normally is limited to a few months. "We find that maximum survival of N. furzeri in the laboratory is less than 12 weeks," the Italian scientists write. This is the shortest lifespan ever to be found in a vertebrate.
Owing to its small size and the possibility of propagation in captivity, N. furzeri "could be used as a convenient model for ageing research," the researchers hold. In fact, the current "favourite" research object of researcher is the zebra fish, which however has the habit of surviving up to five years in laboratories.
Another scientists' favourite is the shrew mouse, which usually survives to see its first birthday, or twelve months. The short lifetime span has an obvious advantage for researchers studying the ageing process and for researchers studying genetic changes from one generation to another. To relate such studies to the human body, vertebrates are preferred study objects.
The N. furzeri species only reaches a length of six centimetres and has adapted perfectly to the harsh and shifting environ in a rapidly drying rainy season water body.
Shortly after the arrival of sufficient water, N. furzeri starts hatching. Only four weeks after hatching, puberty is done with and the fish has reached sexual maturation. Not much time is wasted looking for a mate and reproducing. A new generation of eggs is normally spread out over the waterbed long before the temporal water body is getting dry.
After completing their life cycle, the species enter "a steep age-dependent decrease in fitness," according to the Italian researchers. Independent of the water body's ability to remain a viable environ, N. furzeri passes away due to old age before completing its eleventh week of life.
As the water bed slowly dries in to a desert-like landscape, the new generation of N. forzeri is however secured. The eggs will hibernate until life-awakening water again turns the dry soil into a nutrition-rich environ.
The Italian researchers' attention on the fast-livers however may take them to more comfortable environs all over the world. If they reach fame within the growing ageing science industry, more N. forzeri soon will grow up in laboratories in the northern world than in Zimbabwe's shifting waterbeds.
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