Slicing and Reassembling Toad Salami

It feels as if only a couple of months have passed since I last posted, although I can clearly see that it says Jan 22 there. Here is a quick recap of the last “few” months.

February to April I was focused on processing histological series of developmental serieshistology-photos of pairs of toad species that do and do not have complete tympanic middle ears. Our goal is to see how the development of head structures of eared and earless species is different. I was glued first to the microtome (think “salami slicer”), and then to the microscope (think “salami imager”). Right about the time that I had finished taking photos of each slice of each animal (~4000 photos like the one pictured), I learned that I had been awarded a postdoctoral fellowship from the American Association for University Women (AAUW; see profile here). The award is generally granted to later stage postdocs so that they can pay the bills while they analyze and write up data in the process of preparing for and securing a permanent research position. I am extremely grateful to have been awarded this honor and the timing could not have been more perfect!

Germany 2016 Devo poster.jpgIn May, senior team toad reps (Kim Hoke, Molly Womack, and myself) traveled to
Delmenhorst, Germany for a workshop titled “Linking Evolution and Development of the Auditory System” to present some posters on the toad project (mine is pictured to the right) and meet some fantastic colleagues studying similar questions. Who would have guessed there was such a specific conference just for the exact thing we are focused on!

Near the end of May and into late July, I shifted gears temporarily, and focused on coordinating the “fundamentals” graduate field course with the Organization for Tropical Studies (OTS) called “Tropical Biology: An Ecological Approach” along with co-coordinator Patricia Salerno, TA Victor Acosta, and a slew of amazing, skilled, and enthusiastic visiting professors. This course has been running for over 60 years since the first round with Dan Janzen and Jay Savage, taking students to different ecosystems around Costa Rica in a sort of bootcamp for early grad students. We do “experiment interval training”; at each site students have to design a hypothesis, collect and analyze the data, and present it in oral and written form (~1 week per project), and then move locations and rinse and repeat. Some projects are done alongside a visiting professor, sometimes in groups, and sometimes individually. By the end, students are much more confident and capable researchers. We also put a heavy emphasis on training in science communication, and the (biology graduate) students produce popular science articles, podcasts, and short films about the work they are doing on the course (see course VIMEO page here). Here’s an example film (that still makes me tear up), made by a group of 4 of our students with expert coaching from film producers Morgan Heim and Amy Marquis:

Patricia and I will be teaching the course again next summer (May 22-July 2, 2017), so if you are, have, or know of an early grad student that would benefit from some rigorous practice in developing scientific questions and following through to project completion, please send them our way!

Since the course ended in July, I have been glued to the computer focused on 2 major projects that will be the products of my time as an AAUW fellow.

First, I have just finished up with reconstructing 3D models of the developmental series of toads using a free program called “imod” and those 4000 salami photos I took in the lab. Labmate Molly Womack has written quite a bit about this on her blog, because she has done this for lots of juvenile and adult toads and bestowed me with her 3D reconstruction know-how.

In the video below of the 3D reconstructed ear of an adult toad, you can find the blue annulus, yellow and flat tympanum (the ear bit that we can see from the outside), and turquoise columella, the three famous parts of the middle ear that seem to disappear in a number of toad species. The big round gold part is the inner ear. Green is the operculum, which also transmits low frequency vibrations via the pink opercularis muscle and down through the scapula to the foot.

When I am not tracing these structures in each piece of salami, I am synthesizing information about the developmental timing of these structures in an extensive literature review. Because we believe that shifts in developmental timing are likely responsible for the mysterious loss of ears over 10 different times in this family, having this background of when structures appear across many species will give context and a timeline for the rest of our research. The literature review stretches from papers published in the 1880s up to things coming out this month, combining super-old school morphological observations with cutting edge genomics perspectives on neural crest cell differentiation, and aims to provide some solid hypotheses for future testing. One thing I have learned is that the style of writing in scientific papers sure has changed since 1881 when W.K. Parker published “On the structure and development of the skull in the Batrachia” in Philosophical Transactions of the Royal Society of London:


In the last couple of months I’ve also had the chance to present the toad project in invited talks at the III Amphibian and Reptile Conservation International Symposium in Costa Rica and in a departmental seminar at the Universidad de Los Andes in Bogotá, Colombia. Team toad will be presenting updates on the projects I’ve mentioned above as well as Molly’s latest findings at the Society for Integrative and Comparative Biology (SICB) annual meeting in New Orleans, LA at 2 and 2:30 pm on Jan 5th in room 210.