[extropy-chat] sperm RNA

[Damien Broderick]

Dads deliver more than just DNA

May 13, 2004

http://www.theage.com.au/articles/2004/05/13/1084289787653.html#

Despite the spectre of cloning and the birth of a fatherless mouse, 
scientists have uncovered evidence that men play a more vital role in 
procreation than they may have thought.

Male sperm not only fertilises the female egg, it also delivers male 
chromosomes and messenger RNA, molecules that carry codes which may help 
the embryo develop and grow.

"Men have a greater role in early development than we previously thought," 
said Stephen Krawetz, of Wayne State University in Detroit, Michigan.

Krawetz and colleagues in the United States and Britain have identified six 
messenger RNAs found in sperm and fertilised eggs but not in unfertilised 
eggs.

The finding, reported in the science journal Nature today, suggests that 
messenger molecules are delivered when the sperm fertilise the egg. It may 
also improve understanding of infertility and cloning.

"We have been able to show that in humans, along with delivering the DNA 
component, there is an RNA component which is also delivered. This is the 
first time that has been shown," Krawetz said in an interview.


"Dad is delivering more than just his DNA."

Krawetz suspects the paternal RNA plays an important role in the early 
development of the embryo and believes the research could help to explain 
why cloning is so difficult.

"We think the RNA that is being delivered could possibly act as a 
developmental or mechanistic switch that sets off the correct developmental 
program early on," he said.

In cloning, the egg develops without sperm fertilisation and although it 
can be manipulated or 'tricked' in the laboratory some of the time, if the 
RNA isn't being delivered by the sperm it could explain the very small 
success rate in cloning.

Last month scientists in Japan and Korea reported creating the first mammal 
without using sperm. The mouse is the daughter of two female mice. Although 
bees, ants and some fish and reptiles reproduce without having sex in a 
process known as parthenogenesis, it was thought to be impossible in mammals.

Mammals inherit one set of chromosomes from their mothers and another from 
their fathers. Embryos containing only female chromosomes usually die early 
in the womb and those with only male genetic material are abnormal.

The fatherless mouse sparked headlines and suggestions that males could 
soon be obsolete.

"In contrast, we show that men are not obsolete," said Krawetz.

"Men do have a function," he added.

- Reuters