May 2014

Event Date: 
Wednesday, May 28, 2014 - 18:00 - 18:15
Institution: 
UNSW
Title: 

Regulation of Secondary Metabolites Production in Streptomyces coelicolor

Abstract: 

Streptomyces coelicolor produces a wide array of secondary metabolites that include antibiotics, actinorhodin (Act) and undecylprodigiosin (Red). When analysed for the growth of S. coelicolor on blood containing medium, we found that a functional haemolysin was critical for its growth. Gene knock-out and complementation analysis revealed the expression haemolysin was critical for growth, sporulation and antibiotics production. Total proteome comparison of wild-type and haemolysin deletion mutant indicated a wide range of carbon metabolizing enzymes to be down-regulated. Further analysis of selected targets that could encode phosphomannose isomerase and alpha-mannosidase revealed these sugar processing enzymes to play a critical role on growth, sporulation and antibiotics production in S. coelicolor.

Event Date: 
Wednesday, May 28, 2014 - 19:00 - 20:00
Institution: 
USyd
Title: 

Population genetics and evolution of Cryptococcus gattii : an environmental pathogen

Abstract: 

The yeast species Cryptococcus neoformans and C. gattii cause cryptococosis in humans and a range of animal. Although research on Cryptococcus is generally structured in terms of its importance as a fungal pathogen, human infection is accidental and the fungus mostly lives as an environmental saprotroph. C. neoformans and C. gattii each comprise a number of distinct molecular genotypes that vary in their ecology, their geographic distribution, and various virulence-associated phenotypes. In particular, C. gattii molecular type VGII is responsible for outbreaks that have expanded the fungus beyond its normal geographic range. Our interests lie in understanding the ecology and evolution of C. gattii in the environment, and how these relate to its ability to cause disease. We have found the level of sexual recombination varies by molecular type, and that while in general C. gattii population structure is sexual, this is punctuated by periodic clonal lineages that may be associated with disease outbreaks. Here we refine our analysis using MLST data, haplotype networks and coalesence theory. We find the level of diversity within genotypes to be highly constrained and comparable to some recently evolved plant pathogens, and evidence for purifying selection at the master regulator of mating type. Comparison with other fungi that are causing major outbreaks suggests C. gattii outbreaks may be due to a “perfect storm”, where range expansion and elevated transmission combined with high virulence bring the fungus to new areas with deadly consequences. 

Event Date: 
Wednesday, May 28, 2014 - 18:15 - 18:30
Institution: 
CSIRO
Title: 

Cairneyella

Abstract: 

In September 1999, I collected a small heath plant from a large sandstone outcrop near the Murphy’s Glen campsite in the Blue Mountains west of Sydney. This seedling had been growing in just a few centimetres of sand atop the rock. The shallowness of soil meant its root system was perpendicular to the stem, and spread out like a spider’s web from the base. Heath plants have unusual roots; they’re very fine, being only marginally thicker than a human hair. I took the plant back to the laboratories at University of Western Sydney and carefully cut these hair roots up in small pieces. I surface sterilised the pieces in bleach and placed each piece, numbered and its location in the root system recorded, onto an agar plate. From these tiny root pieces grew a host of very slow growing non-spore producing fungi. Most of these fungi were ericoid mycorrhizal (ERM) fungi – these fungi form a symbiosis with heath plants – facilitating their growth in challenging places such as acid bogs, nutrient poor sands and soils rich in metals such as cadium and zinc. Since 1999, I’ve undertaken quite a bit of work on the most abundant ERM fungus from this one seedling, and with the help of various collaborators we have observed the structures it forms in roots of heath plants, how it enhances the growth of heath seedlings and examined its carbon, nitrogen and phosphorus catabolism. It was, and still is, the most studied Australian ericoid mycorrhizal fungus. 
Upon moving to CSIRO in 2007, I left the last six cultures in the fridge in Dr. Peter McGee’s laboratory and it was here that they remained until 2013 when I retrieved them on Peter’s retirement. Just two of the last six survived the long winter. In late 2013, we had some space on an Illumina run with some other samples – and we sequenced the genome of this fungus. We’ve called it ‘Cairneyella’ after the late Professor John W. G. Cairney. There’s still much to learn about Cairneyella – and I’m seeking collaborators who’d like to share these last cultures and further the body of work on this remarkable fungus.