Battle of sex in genes and the brain

Sex is good for a lot of things. One of the most important is the way in which sex leads to a shuffling of the genetic cards in every individual. Scientists in Cardiff are beginning to build up a picture of what certain genes are doing in the brain and how they affect behaviour. The results, delegates were told in Geneva today, could help researchers find the causes for conditions such as autism.

Professor Lawrence Wilkinson from Cardiff University, UK, said, “With sex, mum and dad can provide their offspring with a new combination of genetic cards – genes - ready to meet the challenges of a changing environment. Another good thing about the way genes are passed down the generations is that they are usually in pairs with one copy provided by mum and one by dad.” This arrangement serves as a form of survival insurance since in many situations when one copy does not work properly, or is missing, the other copy can do the job. The large majority of genes in the mammalian genome obey this rather sensible rule.

However the genes that Professor Wilkinson and his team are most interested in are ‘imprinted genes’ in the brain. These are odd in that they effectively give up the protection by turning off the activation of one of the gene copies, depending on whether the copy came from the mother (maternal imprinting) or father (paternal imprinting).

Scientists have known about the existence of this idiosyncratic group of genes for about 20 years. They have raised a number of questions about their function, and intense debate over the evolutionary reasons for their existence. The most popular hypothesis put forward to date is that imprinted genes are the consequence of a form of ‘internal genomic’ conflict that arises from the differing interests of the mother’s or father’s genes, and this conflict affects the characteristics of the body and behaviour inherited by the offspring. These arise, in turn, from differences of relatedness between the offspring and the parents. “For example, the female can be sure of the extent to which she is related to her child but the male cannot,” said Professor Wilkinson.

It seems that imprinted genes can influence a range of behaviour, from the baby’s ability to suckle all the way through to the complexities of how we think and behave in adulthood. It is likely that imprinted genes exert many of their effects on the developing brain, both in the womb and after the baby has been born, especially in the critical early phases of infancy.

Consistent with this idea there is good evidence for the involvement of imprinted genes in a number of developmental brain disorders. Some, such as Prader-Willi syndrome and Angelman syndrome, are quite rare, but imprinted genes have also been implicated as important players in autism spectrum disorders.

With the increasing use of genetic screening methods that take ‘parent-of-origin’ into account it is very likely that more examples of the effects of genomic imprinting on the risk of abnormal psychological traits and behaviour will emerge in the future. “The work on brain’s imprinted genes is at an early stage and there are many challenges ahead, not least testing the idea that aspects of normal and abnormal brain function can be influenced by a battle of the sexes that is being waged at the level of our genes,” he said.

Provided by Swiss Society for Neuroscience

Related stories:

Marsupials and humans shared same genetic imprinting 150 million years ago
Research published in Nature Genetics by a team of international scientists including the department of zoology at the University of Melbourne, Australia, has established an identical mechanism of genetic imprinting, a process involved in marsupial and human fetal development, which evolved 150 million years ago.
Scientists map imprinted genes in human genome
Scientists at Duke University have created the first map of imprinted genes throughout the human genome, and they say a modern-day Rosetta stone – a form of artificial intelligence called machine learning – was the key to their success.
Thumbs up -- a tiny ancestral remnant lends developmental edge to humans
Subtle genetic changes that confer an evolutionary advantage upon a species, such as the dexterity characteristic of the human hand, while difficult to detect and even harder to reproduce in a model system, have nevertheless generated keen interest amongst evolutionary biologists. In findings published online in the September 5 edition of the journal Science, researchers from the U.S. Department of Energy's Lawrence Berkeley National Laboratory and their collaborators, have uncovered a specifically human 13-nucelotide change concealed in the vast three-billion-letter landscape of the human genome.
Gene enhancer in evolution of human opposable thumb
Scientists have discovered a gene enhancer, known as HACNS1, that may have contributed to the evolution of the uniquely opposable human thumb, and possibly also modifications in the ankle or foot that allow humans to walk on two legs, according to a paper published in Science on Sept. 5, 2008.
Studies spot numerous undiscovered gene alterations in pancreatic and brain cancers
HHMI investigators have detected a multitude of broken, missing, and overactive genes in pancreatic and brain tumors, in the most detailed genetic survey yet of any human tumor. Some of these genetic changes were previously unknown and could provide new leads for improved diagnosis and therapy for these devastating cancers.
New methods identify and manipulate 'newborn' cells in animal model of Parkinson's disease
When cells in the brain are lost through disease or injury, neighboring cells begin to divide and multiply, but only a few areas in the brain are able to produce new neurons. Patients with Parkinson's disease suffer degeneration of certain neurons that reside in an area of the brain called the substantia nigra and project into the striatum. Many of the newborn cells in these areas have not been well described because of limitations of methods used to characterize them.
Arteries from distinct regions of the body have unique immune functions
Human arteries play distinct roles in the immune system depending on their anatomical location, researchers at Emory University School of Medicine have discovered.
Gene associated with pair-bonding in animals has similar effects in human males
Variation in the gene for one of the receptors for the hormone vasopressin appears to be associated with how human males bond with their partners, according to an international team of researchers.

News discussion:

Medicine & Health news