‘Glowing green’ sperm to aid fertility research

A technique which makes sperm glow fluorescent green could be used to aid research into male infertility, scientists have claimed.

Scientists at Oxford University say that have found a way to introduce a synthetic gene – or transgene – directly into a normal, live animal, in such a way that the gene is expressed in mature sperm.

The study, published in the ‘Biology of Reproduction’ journal, involved the introduction of the gene coding for a fluorescent green protein from a jellyfish into sperm precursor cells within the testicles of a hamster – a technique which produced green, glowing sperm.

Hamsters were used in the study, because they have similar sperm to humans, which makes them an ideal model to study human sperm development and how infertility may result when things go wrong.

The Oxford University team said this new method could be “extremely important” for fertility research, because it allowed many different aspects of gene function in sperm to be studied.

The team said that the approach was particularly important, because, unlike many other cells of the body, sperm cells cannot be cultured and genetically modified in a petri dish, due to their small size, unusual shape and short life span outside the body.

Commenting on the study, lead researcher, Dr John Parrington of the Department of Pharmacology in Oxford, said: “Our real aim is to use this technique to study the function of genes that are important during fertilisation and that may cause infertility if they become defective. That’s an important goal given that a recent study found that one in seven British couples have fertility problems and a third of these have an unknown cause.”

One of the areas that Dr Parrington’s team are studying is the mechanism by which sperm entering an egg triggers it to develop into an embryo, rather than remaining in a state of suspended animation.

The scientists say that the technique may also offer the possibility of creating genetically modified animals for use in other research.

Currently, genetically modified mice are created by introducing transgenes into an egg. However, this method is relatively inefficient and attempts to use it to create genetically modified versions of important model species, such as hamsters and guinea pigs have failed, so far.

The team claims that creating transgenic animals from transgenic sperm – genetically modifying the sperm and fertilising a normal egg with it – might help to reduce the numbers of mice used in medical research, as well as open up the possibility of studying gene function in species that are better models than mice for studying certain human diseases.

(KMcA/SP)