I got to thinking about humanized organisms while I was reading about hydra. Hydra make good models to study the biology of aging because they seem to be immortal: they don’t seem to age at all. If we knew how they accomplished it, it might help us understand how to slow aging. How do we know that they don’t age?
Prof. Daniel Martinez observed groups of hydra for years. He carefully fed them and kept them in separate tubes. Each one was observed making buds – little baby hydra – but the old hydra was put into a fresh tube alone every time. The researchers waited for any of them to get old and die… and none did. Well, maybe they didn’t wait long enough? We can only compare them to other creatures in the same weight class.
Longevity tracks body size and time to first offspring. So orcas (weight 1 million grams, first offspring at 25 years) live far longer than voles (weight 10 grams, first offspring within a few weeks of birth). Hydra weigh in at a fraction of a gram and have their first offspring a few days after being born. But they are still alive and reproducing for years, thousands of times longer than the trend would predict.
What allows hydra to accomplish this? How do they regenerate? What’s special about their stem cells that they don’t deplete? Can we study hydra in a way that’s relevant to human longevity?
People have made genetically modified hydra. For instance, they added green fluorescent protein to the hydra to make it glow green under specific circumstances. Even so, to my knowledge, nobody has made a humanized hydra, a hydra engineered to have a human gene. But I find the idea amusing, so I wrote a comic about it. I got some help for the art – thanks to Snowman for their work on this.
I was thinking about humanized hydra and genetically modified hydra and that made me think of the scenario that would undoubtedly result if we were living in a sci-fi story. Maybe the hydra would get super smart or giagantified. A man-sized hydra would be pretty terrifying. Their arms have stingers on them with poison, and they can split open along their length to engulf their prey.
Despite the scary term, it doesn’t actually mean that the creature will acquire human size and intelligence and crawl out of the laboratory and require a breach of the Geneva conventions to subdue. What about studies of aging in humanized hydra? Will that break immortality? Could we screen drugs to rescue it?
Seems like an interesting strategy, but I have not yet found any publications on it. It looks like it’s very difficult to make human genes express properly in Hydra. We are very different from hydra compared to mice, so that’s not very surprising. It looks like the first transgenic hydra were made in about 2006, so it’s a relatively new technology. Maybe we will see some humanized hydra sometime soon.
Things I’ve been reading:
The Last Graduate by Naomi Novik – Absolutely brilliant. Is it woke Harry Potter? Maybe. Is it awesome? definitely. If the subtext of the Hogwarts universe is elitism and earning the right to participate in the arisotcracy… The Scholomance is the exact opposite.
Oglaf made some BRILLIANT Dungeons and Dragons humor. This particular comic is not explicit, but it’s on a very NSFW site.
Things I have been watching:
Further Hydra Reading:
Martı́nez, Daniel E. “Mortality Patterns Suggest Lack of Senescence in Hydra.” Experimental Gerontology 33, no. 3 (May 1998): 217–25. https://doi.org/10.1016/S0531-5565(97)00113-7.
Tomczyk, Szymon, Kathleen Fischer, Steven Austad, and Brigitte Galliot. “Hydra, a Powerful Model for Aging Studies.” Invertebrate Reproduction & Development 59, no. sup1 (January 30, 2015): 11–16. https://doi.org/10.1080/07924259.2014.927805.
Klimovich, Alexander, Jörg Wittlieb, and Thomas C. G. Bosch. “Transgenesis in Hydra to Characterize Gene Function and Visualize Cell Behavior.” Nature Protocols 14, no. 7 (July 2019): 2069–90. https://doi.org/10.1038/s41596-019-0173-3.