Daddy knows best
New Scientist, 03 October 1998
a male mouse never meets his offspring, he still has a hand in how well
they raise his grandchildren. A gene essential for normal maternal
behaviour comes from the father, say researchers in Britain and Canada.
are inherited in pairs, one from the father and one from the mother.
Most are equally active, but some are biochemically labelled, or
imprinted, to determine which of the two copies of a gene will be
expressed. Researchers have now found a gene that appears to be
essential for females to respond appropriately to their young. But
surprisingly, because of imprinting, only the gene that comes from the
father is expressed.
Azim Surani and Eric Keverne at the
University of Cambridge, Louis Lefebvre of Mount Sinai Hospital in
Toronto and their colleagues engineered male mice that lacked a gene
called Mest. They mated them with healthy females and then looked at
how the female offspring raised their own young. They found that the
pups of females that didn't get an active copy of Mest from their
fathers were much more likely to die (Nature Genetics, vol 20, p 163).
more than 80 per cent of the litters, for instance, at least one
newborn was abandoned, left unfed and tangled in its umbilical cord and
placentaand sometimes all the pups were left this way. None of the
mothers with a working Mest gene neglected their pups.
mothers also failed in other measures of maternal behaviour, such as
how long it took them to retrieve a straying pup and how quickly they
built a nest from available wood chips. Normal mothers collected their
pup within 10 minutes, but Mest-deficient mothers didn't manage it at
all during the 15 minutes they were given. And while normal mothers
immediately got stuck into nest building, only three out of eight
mutant mothers could be bothered.
The finding may have
implications for the theory of "parental gene warfare", says Keverne
(see "Where did you get your brains?", New Scientist, 3 May 1997, p
34). Some researchers think that imprinting exists because males and
females have different interests and try to influence their offspring
through a battle of the genes. "It is in the mother's interest to be a
good mother but you could argue it is far more in the father's interest
if the father is investing nothing but his genetic activity," Keverne
But David Haig of Harvard University in Cambridge,
Massachusetts, who developed the parental gene war theory, says "it
doesn't fit at first sight with the hypothesis" since both males and
females need their grandchildren to have good parents. Still, Haig
found it to be "a fascinating paper" and said it was "the first clear
demonstration" of imprinted genes affecting adult behaviour.
new findings will also help researchers unravel the interactions of
other genes known to influence parental behaviour, says Robert Bridges,
a behavioural scientist at Tufts University in Massachusetts. "Is the
same gene involved in both maternal and paternal care, or do separate
genes regulate the parental responses of each sex?"