Universiteit Leiden

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This Week's Discoveries | 29 Mei 2018

29 mei 2018
Niels Bohrweg 2
2333 CA Leiden

First Lecture

Metabolic coupling in bacteria

Shraddha Shitut (IBL/LIC)

Shaddra is a postdoc in the “Origens Center”, a Dutch initiative that aims to bring together a broad range of scientific disciplines to address one of the biggest challenges in science: the origin, or origins, of life on earth and in the universe. Its aim is to spark and facilitate transdisciplinary research between scientists associated with Dutch universities and research institutes. Shaddha’s research interests are: Microbial community interactions, symbiotic associations, intercellular communication; evolution of multicellularity, transitions in individuality.

Bacteria within communities display a wide range of interactions that have either a positive or negative impact on their growth. Cross-feeding is one such interaction that has a positive effect on either one (commensalism) or both (mutualism) individuals. By exchanging metabolites, bacteria can save metabolite biosynthesis cost and hence enhance growth as a consortium resulting in the spread of cross-feeding genotypes in nature. However, it is unclear what physiological effects arise from metabolite exchange between two individuals. How does the metabolite-producing cell cope with the loss of the metabolite upon interacting with a recipient? Using a synthetically designed cross-feeding system in Escherichia coli that exchange amino acids we aim to answer this question. We show an uptake of amino acids by an auxotrophic recipient from a prototrophic donor cell through nanotubes in coculture. Upon quantifying internal amino acids pools, fluctuations were observed in the amino acid levels in both genotypes. Interestingly, this change in internal amino acid pool in the donor cell triggered amino acid production by delaying the feedback inhibition of amino acid biosynthesis. Taken together, our results show how a loss-of-function mutation (auxotrophy) can lead to a functional fusion through metabolic coupling of two independent cells, much like that seen in host-symbiont associations.

Second Lecture, Lorentz Center highlight

Natural thermal convection: Scaling relations and boundary layers


Olga Shishkina (Max Planck Institute for Dynamics and Self-Organization)

Olga is Heisenberg Fellow and head of the “Theory of Turbulent convection” group at the Max Planck Institute for Dynamics and Self-Organization in Göttingen. Her research focusses on the nature of turbulent flows, in particular, the physics of turbulent thermal convection. Research interests in natural and applied sciences and engineering include in particular the large-scale oceanic circulation, wind chill effects in hot and cold regions, supergranulation in the solar upper convective zone, heat and mass transfer in nanofluids, surface-tension-driven convection and vibration-induced convection in low gravity, improvement of the efficiency of technological heating and cooling processes, control of ventilation processes in living quarters and in transport. 

Olga is one of the participants in the workshop “Rotating Convection: from the Lab to the Stars” that is being held in the Lorentz Center from  May 28through June 1.


Thermal convection is ubiquitous in nature and plays an important role in many engineering and technological applications. One of the main problems here is prediction of the global heat and momentum transport, for different flow configurations. In this talk we will discuss some classical convective flow configurations, for which the scaling relations for the global heat and momentum transport can be derived from the boundary-layer equations.

This Week's Discoveries

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