Go to any bar in Boston, and you’ll probably hear people talking about the recent Red Sox triumph in the World Series, or the dreadful traffic on the way to Cape Cod, or which parts of the T are down this time. You usually won’t hear anyone talking about salamander eyes and lizard tails. But last week, a swarm of salamander-studying scientists descended upon Bella Luna, a cozy pizzeria bar nestled away in Jamaica Plains. All evening, live music mixed with lively discussions of animals that can regenerate their body parts.
On July 23-25, Northeastern University hosted the second annual meeting titled “Salamander Models in Cross-Disciplinary Biological Research,” affectionately known as “Sally Summit 2019.” Close to a hundred researchers from all over the world flocked to Northeastern University (and then to the pizzeria bar) to talk about the slimy animals that had brought them all together.
Salamanders are amphibious creatures that resemble wet lizards, but often also possess a set of gills to live underwater. They are famous for being able to regenerate many body parts, including arms and spinal cords. This makes salamanders, especially the Mexican axolotl, a popular lab model for studying the biology of regeneration.
Organization is key
The very first salamander meeting was held last summer in Vienna, Austria, and it welcomed lab leaders from around the world. This year’s meeting on Northeastern’s campus was open not only to principal investigators, but also to postdoctoral researchers and students. Salamander scientists from around the world got together to share their cutting-edge research over a cup of coffee (or a pint).
Among the conference organizers was Northeastern’s very own James Monaghan (recently featured by News at Northeastern). He teamed up with other axolotl lab leaders in the Boston area: Jessica Whited at Harvard University, Catherine McCusker at University of Massachusetts Boston, and Karen Echeverri at the Marine Biological Laboratory in Cape Cod.
The conference was made possible by several sponsors, including the National Institute of Health. To secure the money for hosting a hundred researchers from around the world, the four organizers had to plan the conference quickly and in great detail. “It was… the first time I’d put in an NIH conference grant,” said conference organizer and limb regeneration researcher Jessica Whited, who ended up getting the grant successfully funded. The conference had to be in Boston. “NEU made the most sense,” added Whited.
Unlocking secrets of regeneration
Even though the axolotl salamander is a fan favorite among regeneration enthusiasts, its genome remained unsequenced for a long time. This problem was resolved last year, when a team at the Institute of Molecular Pathology in Vienna, Austria, managed to piece it together. Sergei Nowoshilow, the first author on the study, explained at the conference how the team had puzzled out the huge amount of genetic information (ten times the size of the human genome!). Now axolotl researchers can better study the axolotl’s genetic makeup, inching closer to solving the mystery of arm regeneration.
It’s a daunting task, but we already know a lot. Catherine McCusker of University of Massachusetts Boston revealed that to regenerate, a limb stump must cover the wound with skin and supply it with nerves, so that the tissue can begin to regrow. Cells from different parts of the limb must also send the proper signals to inform the regenerating arm if it should make an elbow or a wrist.
Timothy Duerr, a graduate student at Northeastern’s resident axolotl lab, also discussed how an axolotl limb assumes its proper anatomy. His vividly colored images demonstrated how genes in charge of patterning were activated both in the development and regrowth of limbs.
Besides arms, salamanders can regenerate their nervous system. Alberto Joven Araus of Karolinska Institute in Sweden showed that the Spanish ribbed newt can regenerate its brain cells, with the help of immune cells. The neuroscientist stressed the importance of cooperation between the immune, nervous, and other systems in the body. “They are all working together in all organisms, and we don’t know enough about that,” said Joven Araus.
Katia Del Rio-Tsonis also focuses on the salamander nervous system, specifically on the eye. Her lab at Miami University has pinpointed structures that spring into action after an injury to the eye. A newt eye can regrow its entire lens from a particular part of the iris, and axolotls have black eye pigment that allows the nerve cells of the retina to regenerate.
Salamanders aren’t entirely alone in their regenerative powers. Some reptiles can regrow amputated tails and spinal cords, but these new tails are small and lack important structures. Thomas Lozito of the University of South California suggested that this striking difference is because stem cells in lizard tails are less potent than salamander stem cells. During his talk, the passionate herpetologist awed the audience by showcasing his impressive vivarium of lizards.
Moving research forward
On the last day of the conference, the attendees enjoyed a demo of Northeastern’s brand-new Institute for Chemical Imaging of Living Systems. This microscopy facility is currently manned by Alex Lovely, a graduate student in James Monaghan’s lab who is doing an internship with Zeiss Microscopy on Northeastern’s campus. Lovely showed how to use the ultramodern lightsheet microscope to create a 3D model of an entire axolotl arm and its gene expression. Such novel imaging technologies may transform the ways in which scientists study regeneration.
While we are still a long way from actually regrowing human limbs, the science behind it is certainly underway. This progress is enabled by funding from government agencies like the National Institute of Health. “I hope that going forward NIH can further prioritize resources for basic scientific research because this is what fuels the development of therapeutic approaches in the long term,” said Jessica Whited, one of the conference organizers.