Studying creatures from the depths of our seas to learn more about ourselves is nothing new; the game was pioneered by Edwin G Conklin, who studied Ciona Tunicates in the early 1900s. Today, tunicates are often held under a microscope by scientists in hopes of learning more about human lives as they are the closest living relative of vertebrates.
Botryllus schlosseri, also known as star tunicate, is a common ascidian, with individual organisms growing up to 3mm. They exist in colonies, forming star shapes as they grow from tiny tadpole-like organisms till they settle down on rocks and lead a sedentary lifestyle.
Additionally, they are part of the Chordate phylum, like humans, but have simple embryos and compact genomes, making them a simple model organism. This makes them ideal for study, when compared to mice, which reach old age and don’t accumulate the same changes in neural stem cells as Botryllus does.
The asexual reproductive nature and lifespan of a colony of Botryllus opens up an unlikely path to study neural degeneration.
The asexual reproductive nature and lifespan of a colony of Botryllus opens up an unlikely path to study neural degeneration. Post doctoral scholar Chiara Anselmi notes that “Out of about 1,000 genes that are involved in neural degeneration, we found that 428 are homologous genes shared by humans and Botryllus."
Neurodegenerative diseases are more prevalent amongst the aging population, with around 7.1% of people aged 65+ in the UK being estimated to have dementia. The number only increases with time, with dementia affecting 30% of those aged 90-94.
Studies conducted on Botryllus offer similar patterns; the stem cells in the colony don’t regenerate the same way after around 20 years, mirroring the reduction in neurons seen in elderly humans.
Understanding neural stem cells through the study of Botryllus could prove useful in generating new functional neurons as therapy for Alzheimer’s and other forms of dementia. Although most neural stem cell treatments are still in the experimental stages, studying the neural development of Botryllus could prove to give us insight into the complicated world of neurodegenerative diseases.
It’s pretty wild to think that these tiny little sea creatures might hold the key to solving big human health problems like Alzheimer’s. Who knew studying something as simple as a tunicate could help us unlock the mysteries of aging and regeneration in humans? The ocean really is full of surprises!