Eukaryotic Microbiology: Two Weeks In

Have the second week of Eukaryotic Microbiology in the books (except for some residual grading to complete). So far we've covered Candida albicans and two Fusarium spp. Last week was C. albicans and we discussed two papers. (I'm not including the review articles students read at the beginning of each week.):

• An isochromosome confers drug resistance in vivo by amplification of two genes, ERG11 and TAC1. Selmecki A, Gerami-Nejad M, Paulson C, Forche A, Berman J. Mol Microbiol. 2008 May;68(3):624-41
• Self-regulation of Candida albicans population size during GI colonization.
• White SJ, Rosenbach A, Lephart P, Nguyen D, Benjamin A, Tzipori S, Whiteway M, Mecsas J, Kumamoto CA. PLoS Pathog. 2007 Dec;3(12):e184

And this week was Fusarium and we discussed:

• Comparative genomics reveals mobile pathogenicity chromosomes in Fusarium. Ma LJ, van der Does HC, Borkovich KA, Coleman JJ, Daboussi MJ, Di Pietro A, Dufresne M,... Cuomo CA, Kistler HC, Rep M. Nature. 2010 Mar 18;464(7287):367-73. doi:10.1038/nature08850
• Two Cdc2 Kinase Genes with Distinct Functions in Vegetative and Infectious Hyphae in Fusarium graminearum. Liu H, Zhang S, Ma J, Dai Y, Li C, Lyu X, Wang C, Xu JR. PLoS Pathog. 2015 Jun 17;11(6):e1004913. doi: 10.1371/journal.ppat.1004913

While I planned to discuss each week individually, these end up going well together, plus this is a difficult time of the semester for me guaranteeing I can't write as frequently as I would like.

So we stay within the ascomycota for the first two weeks. Some things that I wanted to emphasize in class and that came from the students:

• What does it mean to be 'wild-type'? This came up with regards to a 'wild-type' genomic sequence. Is the CFTR mutation (the allele that causes cystic fibrosis when homozygous) a mutant genotype? Does the fact that in the caucasian population a cystic fibrosis causing mutation in the CFTR gene occurs with a frequency of 0.025 make a difference? What about the allele that causes sickle cell anemia when homozygous? People who have a 'mutant' allele and a 'normal' allele are more resistant to malaria, so this mutation is potentially beneficial.
• How is phenotypic diversity generated in asexual organisms? This is an important question because sexual reproduction is promotes phenotypic diversity in many eukaryotes. However, there are significant issues associated with sexual reproduction that prevents using it as a simple explanation for phenotypic diversity.
• How do organisms adapt to their environment and is a pathogen really any different from any other organism (short answer is 'no')?
• How do duplicated genes evolve? This (Lui paper) goes hand-in-hand with the Candida Selmecki et al paper and the Fusarium Ma paper.

We'll be revisiting many of these issues throughout the semester. We spend a fair amount of time dealing with specific aspects of the papers, but I try to highlight some of these broader issues. This week we tackle Cryptococcus neoformans and will highlight at least one of the above issues again.

First Eukaryotic Microbiology Classes

Since we do not start classes until after Labor Day, the first week represents a Wednesday, Friday week for my writing intensive Eukaryotic Microbiology course. I designed the course to run on a M/W/F cycle, so this first W/F week might seem problematic, but it is not. In fact, it works out extremely well.

The first day of class (today), involves discussing what is going on in the course and going over the syllabus. Similar to last year, in the first class I try getting students involved by having describe their goals and defining plagiarism. This year I focused the first lecture on the structure of the course and less time going in detail on the syllabus. It was only partially successful because I didn't get through the course set up but got through most of it. Luckily there's time to finish on Friday.

Although I don't get too deep into the syllabus (the students can read), I do cover grades and how they are determined because this is an issue that cuts to the heart of many students. One thing I started doing last year in another class, is determining the course GPA. That is the GPA for the course, determined by the student grades. The last two years my Eukaryotic Microbiology course had a GPA of 3.0 and 2.7. I'm pretty happy with these GPAs overall, it means I am not giving out a ton of A's but the GPA is higher than one might expect for an introductory class (this is not an introductory class and is taken primarily by seniors in the major with a smattering of graduate students).

The class is generally set up as follows:

• Monday: I give a standard lecture introducing the students to an organism and the relevant topics for the week.

• Wednesday: Students present primary research papers. However, they don't actually present the paper, I have them answer some specific questions:

• A. What question is the paper addressing and why do we care?
• B. Which conclusion do you think is the most interesting/important and why?
• C. Pick one figure that you think best supports your favorite conclusion and explain in detail how the data support the conclusion.
• D. What are the limitations of the data?
• E. Why are the conclusions important?

Questions A and E are only answered by the presenters, which is why they are struck out. These questions are derived from a document by Little and Parker (no longer available online, but they were at the University of Arizona). I like these because they focus the students in on a specific aspect of the paper, their favorite conclusion, which may be completely different than the press release or authors' overall conclusion.

The students then focus in on the data that supports that conclusions and not the entirety of the paper. Essentially, I do not want the presenters to reiterate the paper to the class, everyone is required to read the papers so there is no need to reiterate them.

The most difficult part is finding limitations or some issue(s) with the data/interpretation of data. I think students are trained to accept the literature and not rigorously go after the authors and their arguments, which, is in a nutshell, how science works. This one takes time and experience to get good at. Even excellent papers can have issues and I think one of my jobs is to get students comfortable with finding issues.

One thing I haven't told the students about is that the presenters have to give a 30 second elevator talk about the paper. I started doing this several years ago and I think it is extremely important. Basically, if you were an author and someone in the grocery store asked you about your work, how do you explain cogently and succinctly such that they are impressed and glad their tax dollars are supporting the work.

• Friday: Discussion of things. This varies markedly and is dependent on the students. I have a discussion board for them to ask questions, raise issues, provide feedback, etc. I do not post to these boards unless things are going off the rails and try to keep it a student oriented discussion board. (Once a prof posts a comment, all additional comments cease in my experience.)

On Friday, the second day of class, I will model what I expect out of the student presentations. We are reading "Complementary Adhesin Function in C. albicans Biofilm Formation' by Nobile et al. I also provided a review article 'Adhesion in Candida spp.' by Paula Sundstrom.

I will give a 30" elevator talk and then give an oral presentation that covers answers to the above questions A-E. Students are required to provide written responses to questions B-D to get us started.

Starting Monday we really kick into gear, although we will stay with Candida albicans. FYI the topics we are covering are drug resistance and host environmental adaptation.

My goal is to keep blogging about the course throughout the semester.