Project description:This experiment examined the transcriptional response of juvenile amphibian hosts (common frog, Rana temporaria) to two important amphibian pathogens: Batrachochytrium dendrobatidis (Bd) and Ranavirus. Common frogs are non-model organisms which do not have a reference genome.
Project description:How and when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we find that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (KYA), and after no more than 8,000-year isolation period in Beringia. Native Americans diversified into two basal genetic branches around 13 KYA, one in North and South America and the other restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians and Australo-Melanesians, the latter possibly through the ancestors of Aleutian Islanders. Putative relict populations in South America, including the historical Pericúes and Fuego-Patagonians, are not directly related to modern Australo-Melanesians.
Project description:Chytridiomycosis is an emerging infectious disease of amphibians caused by the chytrid Batrachochytrium dendrobatidis (Bd). The disease has been associated with global amphibian declines and is driving the species in the wild to extinction. Using DNA microarray technology we have analysed transcriptional changes in Xenopus tropicalis during the course (7 and 42 days) of infection by Bd under warm (26oC) and cold (18oC) temperatures.
Project description:Global amphibian declines and extinction events are currently occurring at an unprecedented rate. While various factors are influencing these declines, one factor that is readily identifiable is disease. Specifically, the fungal pathogen Batrachochytrium dendrobatidis is thought to play a major role in amphibian declines in tropical and neotropical regions of the globe. While the effects of this chytrid fungus have been shown to be devastating, certain individuals and relict populations have shown resistance. This resistance has been attributed in part to the cutaneous microbiome. Many identified bacterial species that make up the microbiome have shown anti-B. dendrobatidis activity in vitro. One bacteria that is commonly associated as being a member of the amphibian microbiome across amphibian species and shows such anti-B. dendrobatidis activity is Serratia marcescens. Here, we look at transcriptomic shifts in gene expression of S. marcescens (high homology to strain WW4) in response to both live and heat-killed B. dendrobatidis.
Project description:Determining the mechanisms of host-pathogen interaction is critical for understanding and mitigating infectious disease. Mechanisms of fungal pathogenicity are of particular interest given the recent outbreaks of fungal diseases in wildlife populations. Our study focuses on Batrachochytrium dendrobatidis (Bd), the chytrid pathogen responsible for amphibian declines around the world. Previous studies have hypothesized a role for several specific families of secreted proteases as pathogenicity factors in Bd, but the expression of these genes has only been evaluated in laboratory growth conditions. Here we conduct a genome-wide study of Bd gene expression under two different nutrient conditions. We compare Bd gene expression profiles in laboratory growth media and in host tissue (i.e., frog skin). A large proportion of genes in the Bd genome show increased expression when grown in host tissue, indicating the importance of studying pathogens in their infection environment. A number of gene classes show particularly high levels of expression in host tissue, including three families of secreted proteases (metallo-, serine- and aspartyl-proteases), adhesion genes, lipase-3 encoding genes, and a group of phylogenetically unusual crinkler-like effectors. We discuss the roles of these different genes as putative pathogenicity factors and discuss what they can teach us about Bd's metabolic targets, host invasion, and pathogenesis. One 12-plex chip was analyzed from 12 RNA samples extracted from Batrachochytrium dendrobatidis grown in 2 substrates. Six biological replicates were used for each substrate - sterile frog skin and tryptone nutrient broth. The same dye, Cy5, was used for all samples.