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CATEGORIES:Evolution and Development Seminar Series
SUMMARY:The evolutionary origin of neuronal signalling mac
 hinery and animal cell differentiation - Dr Pawel 
 Burkhardt (Sars Centre\, University of Bergen)
DTSTART;TZID=Europe/London:20230426T130000
DTEND;TZID=Europe/London:20230426T140000
UID:TALK199213AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/199213
DESCRIPTION:Multicellularity evolved multiple times independen
 tly in eukaryotes. Choanoflagellates are the close
 st single-celled relatives of animals. Strikingly\
 , these tiny protists can not only alternate betwe
 en unicellular and multicellular states\, but also
  express many genes previously thought to be anima
 l specific (e.g.\, cadherins\, tyrosine kinases\, 
 synaptic proteins)\, making choanoflagellates powe
 rful models to investigate the origin of animal mu
 lticellularity\, the mechanisms underlying cell di
 fferentiation and the ancestry of the neuronal pro
 tein machinery. In the first part of my talk\, I w
 ill show that both\, temporal and spatial cell typ
 e differentiation was likely present in the stem l
 ineage leading to animals. We have reconstructed e
 ntire choanoflagellates and sponge choanocyte cell
 s in 3D through transmission electron microscopy o
 n serial ultrathin sections. Our work has revealed
  several surprises about cell differentiation in c
 hoanoflagellates and constitute an important step 
 in reconstructing the cell biology of the last com
 mon ancestor of animals. In the second part of my 
 talk\, I will present our recent discoveries on ne
 uronal protein homologs found in choanoflagellates
  and ctenophores. We have biochemically and struct
 urally characterized several neuronal protein comp
 lexes from choanoflagellates and gained insights i
 nto their molecular mechanism. In the last part of
  my talk\, I will present ultrastructural data on 
 the ctenophore nervous system. Our analysis indica
 tes that the ctenophore nerve net is wired in a di
 fferent way to what is known from other animals. T
 hese results challenge the paradigm of neuronal ne
 twork activity emerging through cellular diversifi
 cation and provide insights into how many ways to 
 build a neural network. Together\, our work highli
 ghts the importance to include the closest unicell
 ular relatives of animals to understand the evolut
 ionary origin of animal cell differentiation and d
 emonstrates that choanoflagellates and ctenophores
  are at the center stage to understand the evoluti
 on of neuronal machinery and first neurons. 
LOCATION:Online
CONTACT:Nadine Randel
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