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SUMMARY:A vitamin B12 dependent mutualism between a microalga Lobomonas ro
 strata and a rhizobium – Mesorhizobium loti - Vaibhav Bhardwaj\, 3rd yr 
 grad
DTSTART:20150528T123000Z
DTEND:20150528T130000Z
UID:TALK58779@talks.cam.ac.uk
CONTACT:Megan Cooper
DESCRIPTION:Vitamin B12 is an enzyme co-factor and acts on RNA regulatory 
 elements called riboswitches to regulate gene expression. Our group showed
  that many algal species require vitamin B12 and that this requirement is 
 met by co-culturing B12 dependent algae with bacteria that make B12. Using
  the bacterium Mesorhizobium loti MAFF303099 in co-culture with a B12 depe
 ndent alga Lobomonas rostrata\, stable growth of both species occurred. I 
 investigated gene expression of bacteria in co-culture vs free-living stat
 e. The results indicated that there is some differential gene expression a
 nd that two factors are important – the time at which gene expression is
  quantified and the role of a putative riboswitch in regulating gene expre
 ssion. As a result\, I made promoter-reporter constructs to allow for repe
 ated measurements of gene expression to capture the dynamic nature of nutr
 ient exchange and growth on gene expression. In addition to this work\, I 
 have shown that different strains of M. loti such as R7A and a mutant lack
 ing the symbiosis island called R7ANS are able to grow in co-culture with 
 L. rostrata. This result indicates the possibility of wider vitamin sharin
 g between the algae and bacteria. I am also making a vitamin B12 mutant to
  use in competition experiments where I will test the robustness of the mu
 tualism to cheating strains of M. loti. Lastly\, using various microscope 
 techniques I am investigating the nature of the interaction between the al
 ga and bacterium. 
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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