Seminar Series – 17 Mar
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SymbNET Online Seminar Series
Monthly seminars on host-microbe symbiosis, genomics, and metabolomics, with two talks from SymbNET researchers.
The seminars are open and free to all, but registration is required.
Please register once for the entire seminar series.
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15:00 WET / 16:00 CET
Affiliation: University California, San Francisco (UCSF)
Title: Short-range quorum sensing controls horizontal gene transfer at micron scale in bacterial communities.
Abstract: In bacterial communities, cells often communicate by the release and detection of small diffusible molecules, a process termed quorum-sensing. Signal molecules are thought to broadly diffuse in space; however, they often regulate traits such as conjugative transfer that strictly depend on the local community composition. This raises the question how nearby cells within the community can be detected. Here, we compare the range of communication of different quorum-sensing systems. While some systems support long-range communication, we show that others support a form of highly localized communication. In these systems, signal molecules propagate no more than a few microns away from signaling cells, due to the irreversible uptake of the signal molecules from the environment. This enables cells to accurately detect micron scale changes in the community composition. Several mobile genetic elements, including conjugative elements and phages, employ short-range communication to assess the fraction of susceptible host cells in their vicinity and adaptively trigger horizontal gene transfer in response. Our results underscore the complex spatial biology of bacteria, which can communicate and interact at widely different spatial scales.
15:30 WET / 16:30 CET – Jonathan Howard, FCG-IGC
Affiliation: Host-Pathogen Co-evolution Lab, FCG-IGC, Portugal
Title: The maintenance of avirulence in Toxoplasma gondii.
Abstract: The transmission of T. gondii is dependent on avirulence, guaranteeing lifelong parasitism. The selective cost of infection to the host is not balanced by any competing advantage; the optimum strategy for the host is to defeat the parasite. Thus the avirulent state has to defend itself against the Scylla of rapid elimination by host immunity and the Charybdis of virulence resulting in acute death of the host. I will discuss a novel aspect of this phenomenon, in which host and parasite conspire to limit the intensity of the initial immune attack, allowing the parasite to escape and encyst in the brain.
SymbNET Seminars