Approximately one in six people worldwide is affected by infertility, according to the World Health Organization, and one in every 22 children in Australia is born via assisted reproduction. With a 78% failure rate, each IVF cycle can be an emotional rollercoaster that often ends in heartbreak.

“Male infertility plays a role in around 30% of cases, due to problems such as low sperm count, reduced motility or movement or poor sperm quality,” says Professor Majid Warkiani from the School of Biomedical Engineering at the University of Technology Sydney (UTS).

“While much work has been done around selecting eggs and embryos to boost the success rates of IVF, sperm selection, an essential component in assisted reproduction, is by far the most neglected step in regard to technological innovation,” he says.

To tackle this problem, researchers from UTS and NeoGenix Biosciences, a UTS-born start-up, have created and tested a new microfluidic sperm selection device that provides a more reliable process for selecting high-quality sperm.

Traditional sperm selection methods, such as density gradient centrifugation and swim-up, can cause DNA fragmentation and cell death, leading to unsuccessful IVF cycles.

“This new technology is a 3D printed, biologically inspired microfluidic sperm selection device, which replicates the female reproductive tract and the natural sperm selection process, where only a small percentage of total sperm reach the egg,” Professor Warkiani said.

“We conducted extensive testing against conventional IVF selection methods, with the new method showing an 85% improvement in DNA integrity and an average 90% reduction in sperm cell death. The sperm selected by our method also demonstrated better recovery after freezing than traditional methods,” he said.

The study results were recently published in Nature: Microsystems & Nanoengineering.

The researchers have partnered with Monash University and Australian IVF clinics to implement the technology into clinical practice. They hope the device will provide help for those struggling with infertility and reduce the number of unsuccessful IVF cycles.

“A key question for the study of such different microbial strategies is how to define microbial ecological niches in the first place,” says Prof. Dr Bas E. Dutilh. Until now, this has mainly been done based on subjective environmental parameters, which hardly allow unbiased quantification of the niche. The bioinformatician from the Cluster of Excellence “Balance of the Microverse” at the University of Jena, together with researchers from Utrecht University, has therefore used a novel — data-driven — method to describe microbial niches, in which the species community itself is considered the decisive environmental factor instead of external habitat conditions. This works because microbial communities adapt rapidly to their environment, so their composition reflects the sum of all environmental factors.

Most microbial habitats dominated by generalists

For their study, the researchers analysed and quantified thousands of metagenomic data sets from different microbial samples from all over the world. “We found that in most habitats, generalists are dominant,” says Dutilh. The researchers were initially surprised by this finding, as they had assumed that in local niches, specialists might prevail because they are better adapted to the particular conditions. But they found that competing generalists could grow much faster and thus gain dominance in the niche. “For the generalists it’s hit-or-miss, though; either they make it or they don’t. This makes them quite variable in their presence. Specialists are more stable in their niche, albeit at low abundance.”

And there was another result that the researchers had not expected: The genomes of the generalists are not particularly large. “This was previously assumed because metabolic flexibility was thought to generally require a larger genome,” reports Dutilh. But as it turns out, the correlation between niche range and genome size is more complex. “We discovered two contrasting evolutionary strategies: In habitats with relatively low local biodiversity, such as animal-associated microbiomes, the specialists have a relatively small genome. In highly biodiverse habitats such as soils, the genome of the specialists is significantly larger.”

The genomes of generalists are more variable than those of specialists, with genes coming and going during evolution. This allows them to integrate genetic information from other organisms through horizontal gene transfer and thus to adapt rapidly to the local niche. “We also see specific functions that are associated with horizontal gene transfer in generalists’ genomes,” according to Dutilh. The functions associated with specialists are much more diverse, often related to very specific metabolic processes. The genomes of specialists are evolutionarily stable, unlike those of generalists.

“In conclusion, our analysis sheds new and unexpected light on microbial niche range strategies throughout the microbial tree of life,” Bas E. Dutilh is convinced.