Tag Archives: pathogen

Candida White-Opaque switching

Blogging on Peer-Reviewed ResearchA paper in PLoS Biology from Sandy Johnson’s lab entitled “Interlocking Transcriptional Feedback Loops Control White-Opaque Switching in Candida albicans discusses phenotype switching in the human pathogenic fungus Candida albicans. Why is the important?

“White-opaque switching is an epigenetic phenomenon, where genetically identical cells can exist in two distinctive cell types, white and opaque. Each cell type is stably inherited for many generations, and switching between the two types of cells occurs stochastically and rarely—roughly one switch in 10^4 cell divisions”

white-opaque coloniesThere is also a review by Kira O’Day to discuss the implications of the findings. Understanding this sort of developmental and epigenetic signaling is important to better know how fungi adjust and interact with their environment. However, the authors do conclude that White-Opaque switching is exclusive to Candida albicans so aspects of this research only directly applicable to studies in this system. Phenotype switching is an active area of research for Candida biologists – some nice micrographs and SEM of the different cell morphologies can be seen at Prof. Joachim Morschhäuser’s page (and linked to the right).

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Exploring CUG codon evolution in Candida

A recent PLoS One article “A Genetic Code Alteration Is a Phenotype Diversity Generator in the Human Pathogen Candida albicans” finds some pretty dramatic changes in gene expression and phenotypes by replacing the tRNAs for CUG back to Leucine (Leu; in the standard genetic code) from their meaning of Serine (Ser) in these Candida species. The CUG codon transition in some Candida spp has been of interest since it is an example of a recent change in the genetic code and provides a comparative system to study the mechanism and genome changes of how a genetic code shift is manifested.

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Fungal Genetics 2007 details

I’m including a recapping as many of the talks as I remember. There were 6 concurrent sessions each afternoon so you have to miss a lot of talks. The conference was bursting at the seams as it was- at least 140 people had to be turned away beyond the 750 who attended.

If there was any theme in the conference it was “Hey we are all using these genome sequences we’ve been talking about getting”. I only found the overview talks that solely describe the genome solely a little dry as compared to those more focused on particular questions. I guess my genome palate is becoming refined.

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Genomes of honeybee pathogens

A.apisBlogging about Peer-Reviewed ResearchThe Baylor sequencing center has published the genome of two honey bee pathogens. Recently Baylor and collaborators published a slew of honey bee genome papers and it is great that they have also chosen to follow up on the parasites as well.

The group published the genomes of the bacteria pathogen Paenibacillus larvae and fungal pathogen Ascosphaera apis. A. apis is in the Onygenales clade which also includes the fungal human pathogens Coccidioides, Histoplasma, and Blastomyces.

Currently the genome annotation is limited to the bacterial genome where many ab initio gene prediction programs exist and no annotation is provided for A. api. We should be able to apply gene prediction parameters trained from other Onygenales fungi to get a resonable annotation. Study of this pathogenic genome may also provide insight into the evolution of this clade of fungi which contains most of the primary fungal pathogens of humans.