Sperm no longer needed for reproduction

Japanese researchers have demonstrated for the first time how mammals can reproduce without a male, leading to the birth of apparently healthy baby mice by mixing two sets of female genes inside an egg.

Experts said it will be a long time before men are relegated to the role of bystanders in human reproduction. But the latest experiments suggest that laboratory tricks can essentially eliminate the need for fertilization - at least in mice.

Two female mice were created in the experiments at Japan's Tokyo University of Agriculture. One of the mice, named "Kaguya," has been raised to adulthood, has mated normally and has given birth to a litter of pups free of any obvious birth defects. The results are reported today in the journal Nature.

Female-only reproduction is common in the insect and reptile worlds, but there is no evidence yet that it can happen in humans or other primates. Among the many practical hurdles: One of the sets of female-derived mouse genes came from a very early-stage egg not readily found in an adult human, report sfgate.com

According to canada.com the Tokyo University of Agriculture researchers created female-only eggs from the genetic material in eggs from two different mice. From 457 of these engineered eggs, only two live mice were born and only one survived to adulthood.

The scientists named the mouse Kaguya, after a Japanese fairy tale character.

The discovery may shed light on why mammals need genes from each parent to survive.

The technique has few applications beyond the research world and probably wouldn't be attempted by humans because of the high failure rate, the doctors said.

Before Kaguya’s birth, scientists had generally thought this impossible because of a phenomenon known as "mprinting" that requires mammalian embryos to have a male and female input to develop normally. The achievement at the Tokyo University of Agriculture has shed important new light on the workings of imprinting, with implications for fertility treatment, livestock breeding and therapeutic cloning.

Mammals are the only group of animals that do not sometimes reproduce by parthenogenesis, a process in which unfertilised eggs start to develop on their own and produce healthy offspring. Aphids and turkeys are among the species that employ it, and some lizards breed exclusively in this way.

Tomohiro Kono, leader of the Tokyo team, whose findings are published today in the journal Nature, claimed Kaguya as the first example of a mammal born by parthenogenesis. This, however, has been challenged as she has two parents rather than one, and did not develop from a single unfertilised egg.

What is beyond dispute is that she is the first mammal to be born without a father. Even female clones such as Dolly the sheep technically have a father — the male that sired the female adult from which they were cloned, inform timesonline.co.uk