Tiny, swimming rotifers have become an ideal focus of scientific study due to their transparency and easy observability under a microscope. Being able to grow them in laboratory cultures provides unique insights into their corner of the animal kingdom that would otherwise be challenging to obtain.
However, scientists faced limitations in their experiments with rotifers due to the inability to manipulate their genetics effectively. Thanks to the joint efforts of Kristin Gribble and David Mark Welch at the Marine Biological Laboratory (MBL), this challenge has been overcome by developing a method using CRISPR-Cas9 to precisely alter the rotifers' genomes. This technique allowed the editing of two genes and introducing a new genetic sequence that could be inherited through generations.
According to Mark Welch, the senior scientist at MBL, this method offers a practical way to generate a large number of genetically altered rotifers quickly. This breakthrough will not only benefit their lab but also open doors for more researchers to work with these animals, leading to advancements in studying aging, DNA repair mechanisms, and other fundamental biological questions.
Developing a microscopic, water-dwelling lab animal
The team at MBL is determined to expand the roster of model organisms used in scientific research by including rotifers. These tiny invertebrates offer valuable insights into evolution, development, and various aspects of biology due to their close ties to ancestral animals.
To make rotifers genetically tractable, the researchers developed a method using CRISPR-Cas9, funded by MBL Interim Director Melina Hale of the University of Chicago in 2017. CRISPR-Cas9 allows precise alterations to genes by making cuts in DNA.
Capturing the fast-moving rotifers proved challenging. To solve this, Haiyang Feng, a postdoctoral scientist at MBL, used an anesthetic and a high-viscosity solution to slow them down, enabling successful injections of the gene editing system into the female rotifers' bodies, specifically the part that supplies nutrients to the eggs. The mutations were passed down through generations of offspring.
Through this process, the team inactivated the vasa gene, leading the rotifers to stop reproducing after a few generations. They also turned off the mlh3 gene, preventing the production of male offspring, and introduced a section of genetic code containing “stop” instructions into mlh3 to achieve the same effect. Now, rotifers can be considered a promising addition to the group of genetically tractable model organisms widely used in research.
New possibilities for rotifer research
Both researchers, Gribble and Mark Welch, are eager to utilize the CRISPR-based method for their individual research with rotifers. Gribble, an associate scientist at MBL, aims to delve into how mothers' age impacts their offspring's traits, particularly focusing on mitochondria, the energy-producing component of cells. This new technique will enable her to tag or modify mitochondria to explore their role more effectively.
On the other hand, Mark Welch plans to leverage the CRISPR-based method to study the molecular mechanisms behind a specific rotifer species' remarkable ability to revive after complete desiccation. His research will shed light on how these rotifers repair DNA damage during the process.
The potential of this new tool excites both researchers. They believe that, combined with the ease of raising rotifers in the lab, it will unlock answers to numerous questions that haven't even been considered yet, expanding the scope of rotifer research significantly.
Source: Marine Biological Laboratory