Tuesday, March 04, 2008
Martian Avalances Caught in the Act
Image Credit NASA/JPL-Caltech/University of Arizona.This is amazing, an avalanche on the escarpment of the Martian North Pole caught by the Mars Reconnaissance Orbiter. You can get an abbreviated description at the NASA Science Page, and a full description at the MRO site. If you are feeling active you can dig out the before images and make a comparison with the avalanche images. Tom also has a story on this, as does the Bad Astronomer.
The MRO also has a fantastic image of Earth and the Moon taken from Mars. The Bad Astronomer also has a story on that.
# posted by Ian Musgrave @ 7:39 pm 
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That is pretty amazing. Just finished reading Red Mars by Kim Stanley Robinson, so any Mars related goodies very welcome!
Not entirely on topic (actually not on topic at all), have you seen this paper Ian. It looks at the evolution of the type III secretion system. Seems like a good read from my relatively uninformed perspective. Maybe one for a Pandasthumb write up?
McCann, H.C. and Guttman, D.S. (2008) Evolution of the type III secretion system and its effectors in plant-microbe interactions. New Phytologist, 177, 33-47.
Many bacterial plant pathogens require the type III secretion system (T3SS) and its effector proteins (T3SEs) to invade and extract nutrients from their hosts successfully. While the molecular function of this system is being studied intensively, we know comparatively little about the evolutionary and ecological pressures governing its fate over time, and even less about the detailed mechanisms underlying and driving complex T3SS-mediated coevolutionary dynamics. In this review we summarize our current understanding of how host-pathogen interactions evolve, with a particular focus on the T3SS of bacterial plant pathogens. We explore the evolutionary origins of the T3SS relative to the closely related flagellar system, and investigate the evolutionary pressures on this secretion and translocation apparatus. We examine the evolutionary forces acting on T3SEs, and compare the support for vertical descent with modification of these virulence-associated systems (pathoadaptation) vs horizontal gene transfer. We address the evolutionary origins of T3SEs from the perspective of both the evolutionary mechanisms that generate new effectors, and the mobile elements that may be the source of novel genetic material. Finally, we propose a number of questions raised by these studies, which may serve to guide our thinking about these complex processes.
Not entirely on topic (actually not on topic at all), have you seen this paper Ian. It looks at the evolution of the type III secretion system. Seems like a good read from my relatively uninformed perspective. Maybe one for a Pandasthumb write up?
McCann, H.C. and Guttman, D.S. (2008) Evolution of the type III secretion system and its effectors in plant-microbe interactions. New Phytologist, 177, 33-47.
Many bacterial plant pathogens require the type III secretion system (T3SS) and its effector proteins (T3SEs) to invade and extract nutrients from their hosts successfully. While the molecular function of this system is being studied intensively, we know comparatively little about the evolutionary and ecological pressures governing its fate over time, and even less about the detailed mechanisms underlying and driving complex T3SS-mediated coevolutionary dynamics. In this review we summarize our current understanding of how host-pathogen interactions evolve, with a particular focus on the T3SS of bacterial plant pathogens. We explore the evolutionary origins of the T3SS relative to the closely related flagellar system, and investigate the evolutionary pressures on this secretion and translocation apparatus. We examine the evolutionary forces acting on T3SEs, and compare the support for vertical descent with modification of these virulence-associated systems (pathoadaptation) vs horizontal gene transfer. We address the evolutionary origins of T3SEs from the perspective of both the evolutionary mechanisms that generate new effectors, and the mobile elements that may be the source of novel genetic material. Finally, we propose a number of questions raised by these studies, which may serve to guide our thinking about these complex processes.
# posted by 
: 9:04 pm
: 9:04 pm
No, I hadn't seen that paper! It's wonderful. I have to share it with the other flagellum buffs (and do a PT post!). Many thanks!
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