Lichtgedanken 03

Rubrik 64 How fish made the move to land The garfish’s cucullaris muscle give insight into the evolution of terrestrial vertebrates The garfish has been swimming in the waters of our planet for more than 140 million years, yet it still holds secrets. Evolutionary biologists from Jena have unravelled one of these secrets gaining important information about how fish developed into terrestrial vertebrates. Benjamin Nau- mann (photo below) and Prof. Lennart Olsson from the In- stitute of Evolutionary Biology have succeeded for the first time in correctly identifying the »cucullaris« muscle in this fish species. This muscle shows many similarities with the cucullaris muscle of terrestrial vertebrates. The scientists reported on their research results in the specialist journal »Evolution & Development« (DOI: 10.1111/ede.12239). »We have corrected an error made over a century ago, be- cause in earlier investigations a different muscle was clas- sified as the cucullaris muscle in the garfish,« says Benja- min Naumann. The evolutionary biologists are interested in the muscle which connects the head to the shoulder girdle in particular because it is present both in ancient fish and in mammals, although its function has changed substantially during evolution. »In fish, the head rests di- rectly on the shoulder girdle, which means that the head cannot move independently from the body,« explains Prof. Olsson. This direct connection has been done away with in terrestrial vertebrates. They developed a neck which enabled them to move the head independently from the torso. This new study in Jena has made it clear that in the garfish, too, this muscle is present between the body and the head. Previously, researchers had erroneously assumed that a different muscle near the gills was the cucullaris. »The po- sition of the cucullaris muscle is important because it re- veals to us that it is formed exactly as it is in mammals, for example,« says Naumann. »Developmental biology there- fore shows us a homology in this case indicating that the muscle has a common evolutionary origin in both animal groups.« sh What makes mushrooms »magic«? »Magic mushrooms« have their strong psyche- delic effect due to a sub- stance called psilocybin, which has been known for nearly 60 years. One mystery remains, ho- wever: how exactly do mushrooms of the genus Psilocybe (on the photo) form this active substance? A team led by Jena-based natural substance and fungi expert Prof. Dirk Hoffmeister has now solved this mystery. The researchers suc- ceeded in identifying the enzymes that help the mushrooms to form their magic substances. In addition, through their re- search they established that the biosynthesis occurs in a diffe- rent order from that described in earlier studies. Their results appear in the journal »Zeitschrift Angewandte Chemie« (DOI: 10.1002/anie.201705489). Using the model bacterium Escherichia coli , it was possible to produce the previously identified enzymes. In this way, Hoff- meister and his colleagues were able to reproduce the synthe- sis of the active substance and produce psilocybin without fungal cells. In future, this very effective molecule could be produced more easily in this fashion, as apart from its use as a recreational drug, this substance also has useful healing properties. In small doses, for example, it can reduce anxiety in patients with life-threatening cancers or relieve the sym- ptoms of depression and lethargy. MR How mammalian teeth get their shape The teeth of hairless dogs are giving scientists clues to the de- velopment and evolution of teeth in mammals. Hairless dogs differ from other dogs not only due to their lack of fur, but also in the number and nature of their teeth. Researchers from the Max Planck Institute for Evolutionary Anthropology in Lei- pzig and Friedrich Schiller University Jena have re-examined almost 100-year-old skulls and teeth of hairless dogs from the collection of Jena’s Phyletic Museum, and they have establis- hed that a gene called »FOXI3« is involved in the development of teeth. They presented their results in the journal »Scientific Reports« (DOI: 10.1038/s41598-017-05764-5). The team, led by associate professor Kornelius Kupczik and Prof. Martin S. Fischer, was able to show that in the hairless dogs, nearly all the permanent teeth that replace milk teeth (i.e. incisors, canines and premolars) were missing, while the molars were present. It was also noticeable that on these teeth, certain dental cusps on the side nearest the tongue had not developed. The researchers assume that »FOXI3« also plays a role in the development of teeth in other mammals, including humans. US