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Wellcome Trust Research Round-up: 1/9/14

1 Sep, 2014

Our fortnightly round-up of news from the Wellcome Trust research community…

Genes linked to development of glaucoma

N0022146 Testing for GlaucomaA new study funded by the Wellcome Trust and Fight for Sight has identified four new gene locations associated with glaucoma, an eye condition that can lead to blindness and visual impairment. It is hoped the finding could lead to earlier diagnosis and new therapies for treating the condition.

Glaucoma is the leading cause of irreversible blindness in the world. It is caused by damage to the optic nerve, usually due to the eye pressure inside the eye (intraocular pressure) being too high because eye fluid does not drain properly.

In the study published in Nature Genetics, researchers carried out a meta-analysis of more than 35,000 people from seven countries, including subjects of Asian and European descent, with data drawn from the International Glaucoma Genetics Consortium (IGGC).

A site on the ABO gene, which determines blood group, is one of the locations identified, and higher eye pressure appears to be linked to blood group B.

The study also found that a genetic change in the ABCA1 gene is associated with an increased risk of developing both high inner eye pressure and glaucoma. ABCA1 is a major regulator of cellular cholesterol and lipid levels, although further research is required to understand how this mechanism works in the eye.

Early diagnosis of glaucoma is crucial because if it is treated early enough, damage to vision can be prevented. In future it may be possible to provide intensive screening to those identified as being at higher genetic risk.

Professor Chris Hammond from the Department of Twin Research and Genetic Epidemiology at King’s College London, who directed the study, said: “Although eye drops are already available to treat glaucoma, these are not always effective. These findings help us to understand why some people get glaucoma and explain why the condition tends to run in families.”

Male fruit flies’ chemical demand for monogamy

fly sexA new study in The Journal of Cell Biology provides an insight into how male fruit flies

improve their reproductive success by stopping females from mating with other flies.

In addition to sperm, semen carries products that foster sperm survival, promote egg fertilization, and serve other functions that optimise a male’s chances of passing along his genes.

In male fruit flies’, reproductive accessory glands (thought to be equivalent to the prostate gland in humans) secrete signalling chemicals into the seminal fluid that make the recipient females less inclined to mate again with other flies.

But it’s unclear how some of these signalling chemicals are produced and delivered in order to reprogram a female’s behaviour against her own self-interest. Researchers funded by the Wellcome Trust have identified tiny membrane-bound vesicles called exosomes that are secreted into the seminal fluid by the so-called “secondary cells” of male accessory glands.

The authors showed that, after mating, the exosomes fuse with sperm and interact with cells along the female reproductive tract.

When the researchers reduced the number of exosomes produced by secondary cells, the female flies were more inclined to re-mate. This indicates that the exosomes are responsible for the behavioural changes, by interacting with the targeted female cells to overpower normal signalling pathways.

Puberty in girls influenced by one parent more than the other

AS0000131F03 Teenage girlsThe age at which girls reach sexual maturity is influenced by ‘imprinted’ genes, a small sub-set of genes whose activity differs depending on which parent passes on that gene, according to new research published today in the journal Nature.

The findings come from an international study of more than 180,000 women involving scientists from 166 institutions worldwide. The researchers identified 123 genetic variations that were associated with the timing of when girls experienced their first menstrual cycle, by analysing the DNA of 182,416 women of European descent from 57 studies. Six of these variants were found to be clustered within imprinted regions of the genome.

Lead author Dr John Perry, a Henry Wellcome Postdoctoral Fellow at the University of Cambridge said, “Normally, our inherited physical characteristics reflect a roughly average combination of our parents’ genomes, but imprinted genes place unequal weight on the influence of either the mother’s or the father’s genes. Our findings imply that in a family, one parent may more profoundly affect puberty timing in their daughters than the other parent.”

The activity of imprinted genes differs depending on which parent the gene is inherited from – some genes are only active when inherited from the mother, others are only active when inherited from the father. Both types of imprinted genes were identified as determining puberty timing in girls, indicating a possible biological conflict between the parents over their child’s rate of development.

Further evidence for the parental imbalance in inheritance patterns was obtained by analysing the association between these imprinted genes and timing of puberty in a study of over 35,000 women in Iceland, for whom detailed information on their family trees were available.

In other news…

Congratulations to Professor Rob Klose who has been awarded the Royal Society Francis Crick Lecture for his research into how chromatin-based, and epigenetic processes, contribute to gene regulation. Professor Klose has been supported throughout his career by the Wellcome Trust, beginning with his PhD studentship.

Another Wellcome Trust-funded PhD student, Dr Jenny Bangham, has won the Marc-Auguste Pictet Prize for her dissertation “Blood groups and the rise of human genetics in mid-twentieth century Britain”. The prize is given out every other year by the Société de Physique et d’Histoire Naturelle de Genève on a different theme pertaining to the history of science.

Image credits: Testing for Glaucoma – Libby Welch, Wellcome Images, Drosophila melanogaster mating – ImageEditor on Flickr, CC-BY 2.0, Teenage girls – Anthea Sieveking , Wellcome Images

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