December 2011

Event Date: 
Wednesday, January 25, 2012 - 18:00 - 18:15
Institution: 
University of Sydney
Title: 

Vaccinia Virus BTB-Kelch Proteins and the Ubiquitin-Proteasome System during poxvirus infection.

Abstract: 

Vaccinia virus (VACV)—the live-virus vaccine used to eradicate smallpox (Variola virus)—encodes three BTB-Kelch protein (BBK) orthologues, a family of cellular proteins that have demonstrated roles in the Ubiquitin-Proteasome System (UPS). The UPS is the common mechanism by which specific proteins are degraded at specific times inside the host cell. Substrate proteins are multiply-ligated with ubiquitin and are thus flagged for degradation by the 26S Proteasome. If an invading virus were to commandeer such a system it may be rewarded with a unique and powerful solution to avoid the intrinsic cellular defences. BBKs function as UPS substrate adaptors, acting as a link between the ubiquitination machinery and the ubiquitin-ligated substrates themselves.

By encoding BBKs VACV can hijack the UPS and selectively degrade a wide range of host proteins to its advantage; preventing the establishment of an antiviral immune response, transforming the cell into a virus-production factory or enhancing viral spread. Manipulation of the UPS is a phenomena known to play a role in mediating infection in many other viral contexts. The identification of VACV BBK substrates may highlight new mechanisms by which VACV and other viruses overcome the intrinsic cellular defences to mediate infection.

We have previously shown, using fluorescently tagged BBKs, partial colocalisation with the ubiquitinylation machinery, indicating that these proteins act via a common UPS-based mechanism. These results are consistent with partial redundancy observed in BBK mutants and the obstructive effect of UPS inhibitors on poxvirus replication. We are now attempting to further elucidate any potential interactions and dissect the global implications of poxviral interactions with the UPS.

Event Date: 
Wednesday, January 25, 2012 - 18:15 - 18:30
Institution: 
UNSW
Title: 

The impact of petroleum hydrocarbons on microbial diversity in a sub-Antarctic soil; a proxy for soil health

Abstract: 

Anthropogenic sources of contamination remain a legacy throughout the Antarctic Region, with the majority of contamination occurring alongside concentrated human activities at research stations. At Macquarie Island, an Australian Sub-Antarctic territory we have been investigating the impact of petroleum hydrocarbon contamination in the form of Special Antarctic Blend (SAB) diesel fuel on the microbial ecology of sub-Antarctic soils. Whilst bioremediation strategies are currently underway on the Island, there is a lack of petroleum hydrocarbon contamination guidelines specific to Antarctic or sub-Antarctic regions. Additionally, there is insufficient site-specific toxicity data available for remediation end points to be established. Therefore, we have assessed the bacterial and fungal response to increasing concentrations of SAB diesel fuel through a combination of novel culturing methods, flow cytometric analysis of cell numbers and massively paralley pyrosequencing targeting the 16S and ITS genes. Results of this investigation will provide the scientific basis for understanding how much fuel is too much and how clean is clean enough?

Event Date: 
Wednesday, January 25, 2012 - 19:15 - 20:00
Institution: 
University of Technology Sydney
Title: 

The unusual life and cell cycles of extreme Archaea

Abstract: 

Environments that pose chemical and physical challenges to life generally provide a less competitive habitat to those organisms that can adapt to these “extreme” environments. Of the three domains of life, the Archaea have proven to be the most successful in this regard; some environments are almost exclusively inhabited by archaea, with few or no representatives from the bacterial and eukaryotic domains. Archaea in such environments show some unusual properties that are thought to be related to adaption or a lack of inter-species competition. My research has focussed on the molecular cell biology of two model species of extreme archaea; Sulfolobus solfataricus, which lives in sulphurous hot springs with optimal growth at around 80 C and pH 2-3, and Haloferax volcanii, which lives in high-salt environments such as the salt lakes in Australia and the “Dead” sea in Israel. Genomic and cell cycle studies of these species have shown that genetic multiplicity is a common theme in Archaea. Multiple chromosomes, DNA replication origins, and paralogs of cell-cycle related genes are evident in these species. In this seminar, I will present cell cycle and cell biological studies and I will discuss how the basic cell biological features of archaea might relate to their adaption to extreme environments.

Metagenomics has been a hot topic at JAMS in 2011. Playing to this popular theme, Thomas Jeffries of the University of Technology, Sydney opened the final meeting for the year with his metagenomic analysis of taxonomic and functional patterns in South Australia's hypersaline Coorong Lagoon. Thomas and colleagues found shifts in the abundance of cyanobacteria and Archaea linked to a salinity and nutrient gradient along the lagoon, as well as a shift in the abundance of genes related to salinity tolerance and photosynthesis. Surprisingly, despite the extreme range of environmental factors within Coorong, they found these patterns were dwarfed when the lagoon samples were placed in a global context, which showed substrate - in this case, solid or fluid - had a greater influence on taxonomic profiles. Thomas's work shows the importance of scale in the relationship between a microbial community and its environment.

Dear JAMSters,

With the Holiday season well underway I wanted to wish you all lasting health and happiness for the coming new year and thank you for making JAMS such a success this year.

Next year promises to be even better and will start off with a great lineup for our January 25th meeting: