Tag Archives: host-microbe

GradStudent: Two open PhD Positions in Evolutionary Genetics of Fungal Host-shifts

We are seeking candidates to fill two fully funded PhD positions for a period of 3 years in the Applied Evolutionary Ecology research group lead by Henrik H. De Fine Licht at the University of Copenhagen, Denmark (https://plen.ku.dk/english/research/organismal_biology/aee/).

We are looking for committed and enthusiastic graduate students to work with insect-pathogenic fungal genetics, evolution and ecology. We specifically aim to explore how phenotypic plasticity and epigenetic modifications influence the evolution of fungal pathogen host shifts using insect-pathogenic fungi as a model. The project will explore gene transcription profiles and epigenetic modification of artificial fungal host-shift events created in the lab, coupled with phenotypic changes in growth and virulence of fungal pathogens. Further scientific background information can be found in the recent paper by De Fine Licht (PLoS Pathogens 14(5): e1006961). The successful PhD students will thus obtain competences within insect-fungus interactions, fungal genomics and transcriptomics, and applied bioinformatics. We are looking for candidates with experience in any or all of the following areas: Fungal pathogen biology, mycological techniques, molecular genetic laboratory techniques, and computational analysis of genomic sequence data. Most importantly, the successful candidates are enthusiastic, have a good grasp of evolutionary biology and are interested in host-pathogen evolution.

The project is funded by a Danish Research Council Sapere Aude Starting Grant and involves researchers at University of Copenhagen and University of Maryland (USA). The PhD students will be supervised by Associate Professor Henrik H. De Fine Licht and co-supervised by Associate Professor Nicolai V. Meyling.

To apply, please first contact Henrik H. De Fine Licht (Email: hhdefinelicht@plen.ku.dk, include subject-line in email: “PhD student fungal host-shift genetics”). This way, Henrik H. De Fine Licht and the potential applicant can discuss the formal application and requirements (e.g. applicants with English as second language need to provide a copy of a specific English test score sheet and the documentation of academic degrees obtained (diplomas) must be in English/officially approved translation to English) before submission. The deadline for formal application is 1 April 2019, so contact Henrik H. De Fine Licht as soon as possible if you are interested.

Few fungi+host papers

Three papers on some cool fungi that interact with hosts and I recommend them for a good read.

One is coverage of by Ed Yong on rice blast (Magnaporthae orzyae) on paper from Nick Talbot and Gero Steinberg‘s lab on appressorium development in Science this week.

A paper from my lab on role of an expansion of copy number of a chitin-binding domain in the amphibian pathogen B. dendrobatidis.

New Scientist also provides a nice summary of tripartite symbiosis paper on Metarhizium, insects, and plants from Mike Bidochka’s lab.

Dynamics of amphibian pathogen infection cycles

ResearchBlogging.org
Two papers out this week on the population dynamics and epidemiology of the chytrid pathogen of amphibians, Batrachochytrium dendrobatidis (Bd). This is work from the Vredenburg and Briggs labs that includes several decade-long studies of frog declines and the prevalence of Bd.

See Vance in action swabbing a frog

In the Briggs et al paper, they describe a 5-year study on the fungal load in surviving populations of frogs in Sierra Nevada mountain lakes.  They find that adult frogs that have low enough fungal load escape chytridiomycosis and can actually lose and regain infection. They propose that fungal load dynamics are the reason behind differential survival of various populations of mountain frogs. They conclude that:

“Importantly, model results suggest that host persistence versus extinction does not require differences in host susceptibility, pathogen virulence, or environmental conditions, and may be just epidemic and endemic population dynamics of the same host–pathogen system.”

So they propose that differences in the populations that are coming down with the disease is due only to “density-dependent host–pathogen dynamics” not that some populations are resistant. They go on to provide a detailed model of persistence if the host and pathogen, chance of reinfection, and survival of the host which is derived from the long-term study data.  There are many more interesting findings and models proposed in the paper. It also further reinforces (for me) the need to know more about the molecular basis of the host-pathogen interactions and more about how the fungus persists without a host, lifestyle of how it overwinters, and the details of the microbe-host interactions, and the infection dynamic when zoospores disperse from infected frogs.

The Vrendenburg et al paper adresses the dynamics of population decline in the mountain yellow-legged frogs over a periods of 1-5 and 9-13 year study in 3 different study sites at different sampling intervals.  The authors were able to catalog the species decline and conduct skin swabbing to assess Bd prevalence. They found that the fungus spread quickly as it could detected in virtually all the lakes over the course of a year starting with a 2004 survey. The dramatic declines of frog populations in these lakes followed in the years subsequent to the initial detection. This sadly predicts that most if not all of the mountain lakes will go extinct for the frogs as the current tadpoles develop into frogs in the next 3 years and then fall victim to Bd. Based on their sampling work, the authors were also able to correlate what fungal burden predicted a subsequent decline – in populations where more the ~10,000 zoospores were detected in a swab from frog skin, then the frog population was about to experience a sharp decline.  The take-home from this work is that finding ways to keep the intensity of fungal infections down could provide a meaningful intervention that could prolong the viability of the population.

Briggs, C., Knapp, R., & Vredenburg, V. (2010). Enzootic and epizootic dynamics of the chytrid fungal pathogen of amphibians Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0912886107


Vredenburg, V., Knapp, R., Tunstall, T., & Briggs, C. (2010). Dynamics of an emerging disease drive large-scale amphibian population extinctions Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0914111107