The world is full of empty promises and talk in the lab full of brain children, shower thoughts, struggles, minor findings, work adventures and even Eureka moments that rarely escape the corridor or office in which they were born. We do not promise to blog regularly, but as much as possible and from our every-day lives as scientists, including the ups and downs and the stories born around our BBQ on a Friday afternoon. The latter, after all, provides the best stories and worst pictures. Let’s start simple and see what we’re up to in general and more specifically next week.
As evolutionary cell biologists we try to look at things from the bird’s eye perspective. We work almost as much in the dry lab at the desk as we do in the wet lab at the bench. We analyse a variety of organisms and have Trichomonas vaginalis, Euglena gracilis, Chlamydomonas reinhardtii, Bigelowiella natans, Poryphyridium purpureum, Vaucheria litorea, Acetabularia acetabulum and Bryopsis hypnoides currently in culture. Some of the algae initially found their way into our lab as a food source for the only animals that live with us: photosynthetic sacoglossan sea slugs, in our case mostly Elysia timida and Elysia viridis. It turns out that there’s a lot to learn from the algae for other reasons and they’re therefore in the focus of our attention, more recently especially C. reinhardtii. The curiosity of one previous master student, Hendrik Teschke, has also led us to take a closer look at the plastid-to-nucleus ratio in Vaucheria specs. That is rather surprising, but more on that in the future. We guess for now you want to hear more about the slugs. You’re not alone.
It’s fair to say that we are one of the few institutes — unfortunately — that actively work on these curious animals and that is strange when you come to think of it. These sea slugs are the only animals we know that can harbour functional plastids in the cytosol of their own cells. These marine critters seem to blur the clear-cut line we are all so familiar with and which divides the animal and plant world.
There are more than 300 described members of the family Sacoglossa (more commonly known as ‘sap-sucking slugs’) and a few species within this diverse family are known to have a very special ability: they are able to sequester (i.e. specifically isolate) plastids from their algae food source and keep them fully functional in their own animal cells. They are known as photosynthetic slugs. Their ability, known as kleptoplasty (stealing plastids), is not totally uncommon and is also observed among ciliates, dinoflagellates and foraminifera. Yet, among multicellular organisms the sacoglossan slugs are the only ones we know that do this. These sea slugs are considered “photosynthetic“ because the stolen plastids (kleptoplasts) continue to fix CO2 in a light-dependent manner. If you want to know more about the topic I can recommend “A sea slug’s guide to plastid symbiosis” (de Vries et al. 2014 in Acta Soc Bot Pol) or “Plastid survival in the cytosol of animal cells” (de Vries et al. 2014 in Trends Plant Sci). Yes, they’re both from our lab but they’re also the most recent reviews on the issue.
At some point we were culturing five different sacoglossan species in our laboratory simultaneously (Bosellia mimetica, Placida dendritica, Elysia cornigera, Elysia timida and Elysia viridis) but we’ve never been able to get our hands on Elysia chlorotica, the “big sexy green one”. The latter is thought to be the champion in plastid retention (more than 6 months according to the literature), but for years now no one, including us, has been able to find any specimens in the wild. We’ve done collection trips to the Marine Biological Laboratory at Woods Hole, USA, but to no avail. We’re now focusing largely on E. timida and E. viridis, which brings me to next week’s blog: we’re on a fieldwork trip to St. Elba, Italy, to explore a research station for teaching purposes (a bachelor course) and that furthermore gives us the chance to meet E. timida and its food alga A. acetabulum in the wild.
Cessa and Sven