You are what your grandmother ate - epigenetics - grandfather effect too

[Guest guest]

Abstract and link to whole-text article follow the news item.

- - - -

You are what your grandmother ate

* 22:00 13 November 2006

* NewScientist.com news service

* Roxanne Khamsi

http://www.newscientist.com/article/dn10518-you-are-what-your-grandmother-ate.ht\

ml

[foto] The mice on the left-hand side have active AVY genes, giving them

golden fur, while those on the right have silenced AVY genes (Image:

Cropley et al/PNAS)

A mother’s diet can change the behaviour of a specific gene for at least

two subsequent generations, a new study demonstrates for the first time.

Feeding mice an enriched diet during pregnancy silenced a gene for light

fur in their pups. And even though these pups ate a standard, un-enriched

diet, the gene remained less active in their subsequent offspring.

The findings could help explain the curious results from recent studies of

human populations – including one showing that the grandchildren of

well-fed Swedes had a greater risk of diabetes.

The new mouse experiment lends support to the idea that we inherit not

only our genes from our parents, but also a set of instructions that tell

the genes when to become active. These instructions appear to be passed on

through “epigenetic” changes to DNA – genes can be activated or silenced

according to the chemical groups that are added onto them.

Gene silencer

at the Children’s Hospital Oakland Research Institute in

California, US, and colleagues used a special strain of genetically

identical mice with an overactive version of a gene that influences fur

colour. Mice with the AVY version of this gene generally have golden fur.

Half of the mice were given a diet enriched with nutrients such as vitamin

B12 and zinc. These nutrients are known to increase the availability of

the “methyl” chemical groups that are responsible for silencing genes. The

rest of the mice received a standard diet.

The pups of mice on the standard diet generally had golden fur. But a high

proportion of those born to mice on the enriched diet had dark brown fur.

believes that the nutrient-rich maternal diet caused silencing of

the pups’ AVY genes while they developed in the womb.

Passed down

Intriguingly, even though all of the pups in this generation received a

standard diet, those that had exposure to a high-nutrient diet while in

the womb, later gave birth to dark-coated offspring. Their control

counterparts, by comparison, produced offspring with golden fur.

This shows that environmental factors – such as an enriched diet – can

affect the activity of the AVY gene for at least two generations, the

researchers say.

“The results make it clear that a nutritional status can affect not only

that individual, but that individual’s children as well,” says study

member Beckman.

Skin colour

Beckman notes that the AVY gene is linked to weight and diabetes risk. He

adds that there is some evidence that a related gene in humans might

affect skin colour – but it is unknown if it also affects weight.

Even though humans may have a similar gene, they should not make dietary

changes based on the results of the mouse experiment, researchers stress.

“It would be irresponsible to make any prescriptions about human behaviour

based on these findings,” says .

An earlier Swedish study which used historical data of harvests in Sweden,

found that a youngster had a quadrupled risk of diabetes if their

grandfather had good access to food during his own boyhood (see Grandad's

diet affects descendants' health).

http://www.newscientist.com/article/dn2994

Journal reference: Proceedings of the National Academy of Science (DOI:

10.1073/pnas.0607090103)

- - - -

E. Cropley et al.

Germ-line epigenetic modification of the murine Avy allele by nutritional

supplementation

PNAS published November 13, 2006, 10.1073/pnas.0607090103 ( Genetics )

http://www.pnas.org/cgi/reprint/0607090103v1

E. Cropley et al.

*Victor Chang Cardiac Research Institute, 384 Street,

Darlinghurst 2010, Sydney, Australia; {sect}School of Biotechnology and

Biomolecular Sciences and {ddagger}Faculty of Medicine, University of New

South Wales, Anzac Parade, Kensington 2033, Sydney, Australia; and

{dagger}Children's Hospital Oakland Research Institute, 5700 Luther

King Junior Way, Oakland, CA 94609

Environmental effects on phenotype can be mediated by epigenetic

modifications. The epigenetic state of the murine Avy allele is highly

variable, and determines phenotypic effects that vary in a mosaic spectrum

that can be shifted by in utero exposure to methyl donor supplementation.

We have asked if methyl donor supplementation affects the germ-line

epigenetic state of the Avy allele. We find that the somatic epigenetic

state of Avy is affected by in utero methyl donor supplementation only

when the allele is paternally contributed. Exposure to methyl donor

supplementation during midgestation shifts Avy phenotypes not only in the

mice exposed as fetuses, but in their offspring. This finding indicates

that methyl donors can change the epigenetic state of the Avy allele in

the germ line, and that the altered state is retained through the

epigenetic resetting that takes place in gametogenesis and embryogenesis.

Thus a mother's diet may have an enduring influence on succeeding

generations, independent of later changes in diet. Although other reports

have suggested such heritable epigenetic changes, this study demonstrates

that a specific mammalian gene can be subjected to germ-line epigenetic

change.

¶To whom correspondence should be addressed.

I. K. , E-mail:

*

The material in this post is distributed without

profit to those who have expressed a prior interest

in receiving the included information for research

and educational purposes.For more information go to:

http://www4.law.cornell.edu/uscode/17/107.html

http://oregon.uoregon.edu/~csundt/documents.htm

If you wish to use copyrighted material from this

email for purposes that go beyond 'fair use', you

must obtain permission from the copyright owner.