Mice created without fathers By Paul Rincon
The scientists combined two sets of chromosomes from
different eggs Scientists have created two female mice
without fertilising the eggs they grew from, the journal
Nature says. The eggs had two sets of chromosomes from two
female mice, rather than one from the mother and one from
the father as in a fertilised embryo.
The phenomenon, called parthenogenesis, never occurs
naturally in mammals.
Some researchers say the procedures may be applied to stem
cell research, but the scientists who carried out the work
say it would not yet work in humans.
Mammal difference
Tomohiro Kono and colleagues switched off a key gene in the
donor eggs which affected imprinting - a barrier to
parthenogenesis in mammals.
"Insects can reproduce by parthenogenesis. Even chickens can
be made to reproduce by parthenogenesis. I wanted to find
out why mammals are different," Dr Kono of Tokyo University
of Agriculture, Japan, told BBC News Online.
The team injected the genetic material from immature mouse
eggs into mature eggs with their own set of chromosomes.
They then "activated" the combined eggs, prompting them to
start growing as an embryo.
By blocking expression of a gene called H19 in the immature
mouse eggs, the researchers increased the activity of
another gene called Igf2.
Igf2 manufactures a protein responsible for regulating
growth in the developing foetus.
These genes are said to be imprinted. Imprinting means that
some genes are working in maternal DNA but switched off in
paternal DNA, or vice versa. They are unequally expressed.
The genetic manipulation carried out by the researchers gave
the genes a more paternal character.
But as a result of this modification, just two out of 598
mice embryos made it to full term.
Read the rest at BBC News Online
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Posted by Robert Karl Stonjek.