29/06/2019

A lot of research in the life sciences relies on model organisms. Scientists often work with a specific plant, fungus, bacterium, mammal, invertebrate, or cell line. Decades of research have allowed each respective field to develop all the required tools to breed, test, and manipulate these model organisms. By studying them in close detail we have been able to develop an amazingly in-depth, yet continuously expanding, view on biology. In a way, model organisms are the true champions of science.

Steven Boeynaems

Currently, only a select group of organisms holds this elite ‘model’ status. However, if we look around us, there is such a wide variety of organisms alive. I don’t think that any one of us doubts the exciting biology out there waiting to be discovered. Yet, going back to the lab we often find ourselves studying the same model organisms over and over. While I will by no means argue that model organisms have not provided incredible value for the life sciences, I believe it is time for life scientists to step out of their comfort zone. Moreover, with the ever-decreasing cost of sequencing and the broad applicability of CRISPR/Cas9, I would argue that now is a great time to pursue research in ‘new’ organisms.

The lab of Sue Rhee at the Carnegie Institute of Science (Washington D.C., US) is interested in how plants adapt to changing environments, especially considering climate change. While the work of Sue initially almost exclusively involved Arabidopsis, her lab is now pursuing a new path forward. In the 70’s, two plant scientists at Carnegie and Stanford created a mobile laboratory, which was essentially an RV stuffed with lab equipment. With this vehicle, they travelled throughout California. This allowed them to measure photosynthesis rates in plants in their natural habitats. “When measuring the photosynthesis Death Valley plants, they found something really interesting,” says Sue. “Tidestromia oblongifolia, a desert plant that can not only withstand the excruciating heat in Death Valley, but thrives there, has the highest documented optimal temperature for photosynthesis in plants.” She adds: “That record temperature of 47°C hasn’t been broken yet.” 

If we want to arm our crops against the detrimental effects of climate change, looking at evolution for solutions to this problem seems to be an ideal place to start. Sue says: “Rediscovering those seminal papers, I knew this could be something exciting. However, we needed to start from scratch, as no one had really looked closely at this organism in almost four decades”. Growing desert plants in the lab does sound​ challenging though, and the lab indeed had to partner with companies to pull it off. They now have custombuilt incubation chambers that can reproduce the high temperatures and light intensities of the desert environment. “We essentially recreated a mini-Death Valley in our greenhouse,” Sue explains. As they can now grow the plants in the lab, the next step will be to sequence the genome and transcriptome. This will allow them to start elucidating the molecular mechanisms of how desert plants can thrive under such extreme conditions.

Climate change is happening, and we need to start considering how we will maintain agricultural production in the future. Making crops more resistant to stress conditions could be one of the solutions. While this will obviously involve research on the major crops themselves, we should not neglect the plants that are already evolutionary endowed with mechanisms to resist drought and heat. “Nobody cares about desert plants,” Sue jokes. She continues: “But I believe that they will be a part of the solution to making our crops resistant against the effects of climate change. I believe all real solutions for problems like this will come from basic science. We will need to continue to make funding agencies and governments aware of the need for supporting fundamental biology if we want to be able to tackle the challenges ahead of us”.

Besides its effect on agriculture, global warming may present us with problems on other fronts as well. Neglected tropical diseases are expanding towards more temperate regions. For example, Florida and neighboring states have seen increasing incidences of parasitic infections that one mostly associates with the tropics. These infections are caused by protists, small organisms with a – still – very mysterious biology. Naegleria fowleri is one such parasitic protist. It is also known as ‘the brain-eating amoeba’, since it occasionally infects humans, wreaking havoc in the brain leading to the death of the patient within days. There is no treatment for the condition, and as Naegleria prefers warmer waters of lakes and pools, it is expected that global warming may lead to an increased incidence of such infections. While hanging out at a happy hour here at Stanford, this organism came up in discussion. Two postdocs from neighboring labs, Broder Schmidt and Keren Lasker, and I had a crazy idea: What if we could pioneer this organism as a novel model system to gain insights into early eukaryote evolution, and at the same time use that knowledge to think about treatment options for Naegleria infections? Digging into the literature we found a Naegleria species that is not infective, and we are now able to culture these amoebae in the lab. As we speak, we are sequencing its genome and setting up multiple omics experiments.

So why are we doing this? Even though this side project of ours might not immediately lead to big breakthroughs, we are conv​inced that if more scientists would spend some time studying nonmodel organisms, we would dramatically expand our understanding and appreciation of biology. If no one ever bothered studying a weird type of DNA repeats that were present in numerous bacterial genomes, we would not have CRISPR/Cas9 today. Evolution has come up with this enormous diversity in life forms. Within this diversity lie many secrets yet to unravel, secrets that will not only amaze us, but also provide key insights to address present and future challenges.