October 2017

Edgar M. Medina Tovar, a native of Bogotá, Colombia, is currently a PhD student in the Department of Biology at Duke University. In Dr. Nicolas E. Buchler’s lab, Edgar studies the zoosporic fungus Spizellomyces, to develop this non-model organism into a genetically tractable system. The zoosporic fungi comprise a group of fungal lineages that have a fascinating biology and likely hold many clues to the origin of fungi and the Opisthokonts. Although they are full blown fungi, they are particularly interesting to Edgar because they have retained characteristics from the Opisthokont ancestor that we only tend to associate with animal lineages. These fungi have reproductive spores that lack cell wall, crawl on surfaces and swim with a single posterior cillium nucleated from a centriole. Once they find a suitable niche, the spores retract their cillium, form a cell wall and germinate through a hypha-like structure with polarized growth called rhizoid (all this happens within a couple of hours!). At this stage the germinated spore displays more classical fungal behavior, to eventually produce and release hundreds of new zoospores. Edgar believes the mechanisms that underlie this duality and how it is regulated can provide clues to what lies at the core of what it means to be a fungus and how it deviates from the evolutionary trajectory followed by the animal lineage.

Medina_photo - Edgar Mauricio Medina TovarDespite animals and fungi being sibling Opisthokonts, the core transcription factors that control commitment to cell division (E2F and SBF, respectively) and their repressors (Rb and Whi5, respectively) do not appear to have a shared molecular ancestor. Using comparative genomics Edgar showed that SBF, which contains a viral-derived DNA binding domain, was acquired very early in the evolution of fungi by horizontal gene transfer. Also, that this viral-derived transcription factor still coexists with the ancestral E2F in some early-diverging fungi, establishing a hybrid cell cycle control network. Subsequently, the ancestor of Dikarya lost the ancestral E2F and kept SBF. Finally, yeast SBF has an overlapping DNA-binding specificity to that of human E2F. This lead to the working hypothesis of Edgar’s current work: That a viral SBF hijacked cell cycle control in the dawn of Fungi by binding the E2F cis-regulatory sequences of E2F-responsive promoters, and thereby gained the ability to control the G1/S transition and pushing cells to proliferation. Edgar is a recipient of the Duke University School of Medicine Chancellor’s Scholarship in 2012, and for this work, the Meredith Blackwell Award for best grad student talk at MSA 2017. After completing his doctorate, Edgar plans to continue in academia with a postdoctoral position.

What is your favorite fungus and why?

Saccharomyces, if I had to choose one, just as the representative of the hard working guild that brings delicious fermentation products to our life.

What is your favorite thing about fungi?

Fungi are the ultimate éminence grise of the plant world. Fungi are not only arguably the most important plant pathogens, but they rule everything, from plant seed germination to their growth and decay. The establishment of mycorrhizae and endophytism was probably key for the diversification of plants and a necessity for their colonization of land. Also, they are probably the main drivers of nutrient allocation and carbon cycling in our forests. When I see a plant, I see a puppet of a bunch of sly fungi.

Who is your mycology role model?

Much of my current work has strong foundations on the work of Melvin S. Fuller. Reading his papers on zoosporic fungi at a time in which they were emerging as models of cell biology always generates a whirlwind of ideas and reminds me of the power of classical mycology. On the other hand, I think mycology is nowadays such a multidisciplinary science that is hard to have only one role model, so I have many, and would be unfair to say some and leave others out. Nevertheless, a role model should also include characteristics that go beyond “being good at science”. I really look up to PI’s that try to do exciting basic science, do not bend to the “safe fundable zone”, and are great mentors. I am glad there are still many out there and I am lucky to have one as advisor. Unfortunately, it is unclear how you get trained to become a good mentor and is hard to survive and get funded as a PI doing exciting fringe science in the current funding landscape.

What do you do in your free time?

I am all about coffee and food, so I really like cooking and baking. I seem to work with more yeast at home than in the lab. I like sourdough baking and playing with fermentations. Also, I really like road cycling and trail running, allows me to make space to eat even more, though I have relied mostly on running lately because is hard to get the time for long rides and there is an epidemic of bad drivers around here. Also, being in the forest reminds me a bit of home.

Anything else you’d like to share?

I have always liked scientific illustration and I think good figure design is key for a good paper, facilitating communication with the reader. This has led me to sometimes being teased about spending maybe too much time making figures and as my go-to procrastination. I fell in love with it when I discovered Haeckel’s work during my undergrad, fungi have beautiful microscopic and macroscopic structures with incredible elegance.

Teeratas ‘Tas’ Kijpornyongpan is a PhD student from Bangkok, Thailand, where he completed his undergraduate degree. Tas plans to return to Chulalongkorn University in Thailand, his alma mater, as faculty after he completes his PhD at Purdue University. His primary interests are to explore fungal biodiversity in Thailand, as well as to teach and inspire younger generations about mycology. Currently, Tas is in Dr. M. Catherine Aime’s lab, where he works on the groups of early-diverging basidiomycetes called Ustilaginomycotina. The subphylum comprises smut fungi, one of the most diversified plant pathogens infecting many graminaceous plants. Ustilaginomycotina also consists of other members having a variety of life strategies ranging from animal pathogens, plant-associated fungi, and solely saprobic fungi. Tas’s project attempts to understand potential mechanisms that drive the growth from differences in this group of fungi, as well as the process of growth from switching in dimorphic species. Since this group of fungi has been overlooked in terms of biodiversity, Tas is also interested in exploring more unknown species in this lineage under the taxonomic/phylogenetic frameworks. This fungal dimorphism project has been supported by two MSA research awards, the Salomon Bartnicki-Garcia award, and the Graduate Student Fellowship award.

20170811_114515 - Teeratas KijpornyongpanWhat is your favorite fungus and why?

It should be my model species Ustilago maydis for sure. Even though I have no idea how good is the “huitlacoche” (corn gall as a Mexican food), the craziness of U. maydis fungal dimorphism has been helping me stay on this track until now.

What is your favorite fact about fungi?

Fungi have many ways for reproduction¾sexual spores, asexual spores, budding or hyphal fragmentation. Even in sexual reproduction, they are so diverse in terms of sexual compatibility and a number of mating types. Since reproduction is a key property of an organism to exist in the world, it is no doubt that how fungi are much more diversified compared to plants and animals.

Any great stories from field work?

Although I am not very specialized in a field work, there is a little funny story when I helped my advisor survey a site. We were looking around to see what types of fungi could be found in the area. My advisor was interested in rust fungi in particular, so she said what structures to look for as a sign for them. Other people started seeing something, and I tried to do the same. Then I found a crawling plant on the ground, and there are aecia (spore-bearing structures of rust fungi) underneath its leaf. So I grabbed the leaf using a bare hand and told everyone “Look! Here is a rust fungus.” My advisor stared at me for a few seconds before monotonously said “Oh, that is a poison ivy.” I was shocked for a minute before throwing the leaf off, then asked someone for water to wash my hand. Thankfully, there was no any subsequent allergic reaction, maybe because I am tolerant to poison ivy.

What do you like to do in your free time?

I like reading books and playing card/board games for my indoor activities. Photography is a big part of my outdoor hobby. I love not only taking pictures of spectacular scenery and beautiful flowers, but also having shots of tiny mushrooms/fungi on the ground or any pathogens on plants. These type of photos, as well as collected samples, would be invaluable as teaching materials for my future career.