dictyNews
Electronic Edition
Volume 34, number 16
May 28, 2010

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Abstracts
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Dictyostelium amoebae and neutrophils can swim

by Nicholas P. Barry and Mark S. Bretscher

MRC Laboratory of Molecular Biology, Hills Road, Cambridge 
CB2 0QH, England


PNAS, in press

Animal cells migrating over a substratum crawl in amoeboid fashion; 
how the force against the substratum is achieved remains uncertain. 
We find that amoebae and neutrophils, cells traditionally used to study 
cell migration on a solid surface, move towards a chemotactic source 
whilst suspended in solution. They can swim and do so with speeds 
similar to those on a solid substrate. Based on the surprisingly rapidly 
changing shape of amoebae as they swim and earlier theoretical 
schemes for how suspended microorganisms can migrate 
(Purcell EM (1977) Life at low Reynolds number. Am. J. Phys. 45:3-11), 
we suggest the general features these cells employ to gain traction with 
the medium. This requires either the movement of the cell’s surface from 
the cell’s front towards its rear, or protrusions which move down the length 
of the elongated cell. Our results indicate that a solid substratum is not a 
prerequisite for these cells to produce a forward thrust during movement 
and suggest that crawling and swimming are similar processes, a 
comparison we think is helpful in understanding how cells migrate.


Submitted by  Mark Bretscher [msb@mrc-lmb.cam.ac.uk]
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Autophagy in Dictyostelium: genes and pathways, cell death and infection

Javier Calvo-Garrido, Sergio Carilla-Latorre, Yuzuru Kubohara, Natalia 
Santos-Rodrigo, Ana Mesquita, Thierry Soldati, Pierre Golstein  and 
Ricardo Escalante


Autophagy, in press

The use of simple organisms to understand the molecular and cellular 
function of complex processes is instrumental for the rapid development 
of biomedical research. A remarkable example has been the discovery in 
S. cerevisiae of a group of proteins involved in the pathways of autophagy. 
Orthologues of these proteins have been identified in humans and 
experimental model organisms. Interestingly, some mammalian autophagy
proteins do not seem to have homologues in yeast but are present in 
Dictyostelium, a social amoeba with two distinctive life styles, a unicellular 
stage in nutrient-rich conditions that differentiates upon starvation into a 
multicellular stage that depends on autophagy. This review focuses on 
the identification and annotation of the putative Dictyostelium autophagy 
genes and on the role of autophagy in development, cell death and 
infection by bacterial pathogens. 


Submitted by Ricardo Escalante [rescalante@iib.uam.es]
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[End dictyNews, volume 34, number 16]