New research is shining a light on one of genetics’ enduring puzzles – how the workings of the so-called “selfish gene” could be harnessed to control harmful insect populations.

Malaysian stalk-eyed fly (Teleopsis dalmanni). Credit: Paul Richards

By understanding the molecular basis of a selfish gene and the way it operates, scientists believe they could identify novel methods to control certain insects that are globally significant pests and disease carriers.

The research – involving an international team of scientists led by the University of Sheffield – is focusing on what is known as “meiotic drive”, where a selfish gene is able to disrupt the normal pattern of inheritance.

Meiosis is a type of cell division that creates gametes – sperm and egg cells that carry half the genetic material of each parent. When they fuse during fertilisation, they form new offspring.

According to classical genetics, the maternal and paternal versions of each gene in the gametes have an equal chance of being passed onto the offspring. But that process is subverted by meiotic drive, where selfish genes dramatically increase the odds that they will successfully pass on their genetic code.

Dr Alison Wright, from the University of Sheffield’s School of Biosciences and principal investigator in the research, said: “All genes are selfish, but some are more selfish than others. Meiotic drive is a powerful mechanism and, in the insect world, some selfish genes can have a major effect on the numbers of male and female offspring that are produced.”

“Ultimately, this can cause insect populations carrying these selfish genes to go extinct. By studying how that happens at a fundamental level, scientists will be able to exploit that knowledge and put it to good use to control insect populations that are responsible for major disease outbreaks and food shortages.”

The Sheffield-led research has investigated a selfish gene carried by the Malaysian stalk-eyed fly (Teleopsis dalmanni). Using single-cell RNA sequencing, the scientists profiled gene expression in individual sperm cells during their formation, a new technique for investigating the molecular mechanism of meiotic drive.

Dr Peter Price, from the University of Sheffield’s School of Biosciences and the lead author of the study, said: “This novel approach allowed us to find several genes essential for normal sperm development whose activity are altered in the presence of the selfish gene.”

“The selfish gene is able to damage the mobility of rival sperm that carry a Y chromosome, which results in fewer male offspring. Over time, this meiotic drive results in an extremely female-biased sex ratio where very few males are present, with severe consequences for the existence and fertility of the population.”

The Malaysian stalk-eyed fly is not a pest itself, but it offers a valuable insight into how meiotic drive and a selfish gene operate. Next, the scientists will apply their new approach to test the origins of this selfish gene and its long-term consequences for the fate of insect populations.

Source – University of Sheffield