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Mode of action of a widespread toxin-antitoxin bacteriophage resistance system
Friday 19 September
We are surrounded and massively outnumbered by bacteria. Most bacteria are highly beneficial and essential to the environment, ecosystem functions and thus human existence. Even more abundant are bacteriophages, which are viruses that specifically infect bacteria. For example, an estimated 1025 bacteriophage infections occur every second, affecting global nutrient cycles. Bacteria have evolved mechanisms to thwart these invaders, which includes ‘innate immune systems’, such as abortive infection / toxin-antitoxin systems. Following bacteriophage infection, abortive infection and toxin-antitoxin systems elicit a ‘programmed cell death’ that impedes bacteriophage replication and provides population protection by limiting bacteriophage spread. There are currently >20 known abortive infection systems and, with the exception of a few, the molecular basis for bacteriophage resistance is unclear.
We have discovered a two-protein system from Lactococcus lactis, Streptococcus agalactiae and Mycobacterium tuberculosis, which functions via a toxin-antitoxin mechanism. These systems are widespread, found in thousands of sequenced bacterial strains, yet how they work is unknown. In these toxin-antitoxin systems, one protein is toxic to the cell while the other protein protects the cell from this toxicity. Interestingly, the toxin possesses a biochemical activity not previously characterised. We will use a variety of complementary techniques to determine the mode of action and cellular target of this widespread family of toxins in order to understand how they can elicit cell suicide and hence provide bacteriophage resistance.
Role of the pedunculopontine tegmental nucleus in transmitting vestibular information to the hippocampus
15 September 2014
Dr Yiwen Zheng and Professor Paul Smith from the Department of Pharmacology and Toxicology were recently awarded $12,516 from the OSMS Bequest funds for their research on the Role of the pedunculopontine tegmental nucleus in transmitting vestibular information to the hippocampus.
The vestibular inner ear, which contains receptors that respond to angular and linear acceleration of the head, has been studied mainly for its role in controlling balance and keeping the visual images stable on the retina during unintentional head movement. However, in recent years, evidence has accumulated to suggest that this primitive sensory system may also contribute to higher cognitive functions. It has been shown that the hippocampus, one of the brain areas important in integrating multi-sensory information for spatial navigation and memory, undergoes structural, neurochemical and functional changes following vestibular damage. However, our understanding of how hippocampal function may be influenced by vestibular information, is poor. With the awarded grant, we will systematically investigate whether vestibular information is transmitted to the hippocampus via the pedunculopontine tegmental nucleus (PPT), an acetylcholine-containing nucleus located in the brainstem. We will analyse how neuronal responses in the hippocampus and PPT will be affected by vestibular stimulation or inactivation and how hippocampal neuronal responses will be affected by lesions of the PPT using electrophysiological methods. We will also determine whether the influence of vestibular information on the hippocampus is mediated by the acetylcholine system in the PPT by examining the effects of bilateral vestibular lesions on the number of acetylcholinergic neurons in the PPT using immunohistochemistry and the effects of PPT lesions on vestibular stimulation-induced hippocampal acetylcholine release using microdialysis. The results will significantly advance the current knowledge of how vestibular information contributes to higher cognitive function.
International Federation of the Associations of Anatomists Conference in Beijing
10 September 2014
Dr Steph Woodley, along with several other Otago staff members, recently attended the IFAA conference in Beijing, China.
The 18th of the IFAA and the 30th Congress of the Chinese Society of Anatomical Sciences (CSAS) was held at the Beijing International Convention Centre, China from August 8-10. The meeting was attended by approximately 1000 delegates and had a theme of ‘Anatomy, from gross to molecular and digital’. An interesting range of topics was covered over the two days, including talks spanning from clinical, surgical, and imaging anatomy to body donation programmes and medical education. Delegates were treated to four informative and diverse plenary lectures, one of which was presented by Professor Gareth Jones from the University of Otago entitled ‘Finding a context for anatomy as a discipline’. Twenty-five parallel symposia were offered over the three days, alongside 16 free paper sessions, presenting delegates with a diverse range of sessions to attend or contribute to. An Otago contingent of approximately 8 staff members attended the conference, which was in close vicinity to the Beijing National Stadium (aka the ‘Bird’s Nest’, built for the 2008 Summer Olympics). Delegates were also fortunate to either make their own way to, or join a guided tour of, many of the famous attractions that Beijing is renowned for, including the Summer Palace, the Forbidden City and the Great Wall of China.
Proof of Concept Winners
8 September 2014
Dr Elspeth Gold (Department of Anatomy) has won Otago Innovation Ltd’s 2014 Proof of Concept competition. She will use the grant to validate her initial findings on a biomarker she discovered, which may enable differentiation between aggressive and latent forms of prostate cancer.
Dr Monica Gerth (Department of Biochemistry) was runner-up with a proposal to develop antimicrobial enzymes that can be used to prevent “biofilms” from coating medical devices and causing infections.
Congratulations to Elspeth and Monica!
Read more here.