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SUMMARY:Left-right asymmetry determination in amphioxus - Dr Guang Li\, Sc
 hool of Life Sciences\, Xiamen University
DTSTART:20181024T120000Z
DTEND:20181024T130000Z
UID:TALK110407@talks.cam.ac.uk
CONTACT:Martin Minarik
DESCRIPTION:Many bilateral animals develop morphological left–right asym
 metries. In vertebrates\, this asymmetry is established under a sequential
 ly activated gene cascade composing of Cerberus\, Nodal\, Lefty\, Pitx and
  others. To understand how this genetic network has evolved\, we examined 
 the functions of some of these genes in the left-right determination of am
 phioxus\, the most basal living chordate\, using our recently developed ge
 netic manipulation methods. We show that similar to their cognates in vert
 ebrates\, Cerberus\, Nodal\, Lefty\, and Pitx are sequentially activated i
 n amphioxus embryos (first Cerberus\, then Lefty\, Pitx\, and Nodal)\, and
  that knocking- out or overexpressing each of these genes disrupted positi
 oning of left-right organs of amphioxus larvae. We also demonstrate that H
 h signaling is asymmetrically activated (right & left) in the first somite
 s of early neurula where Cerberus asymmetrical expression then occurs. By 
 knocking-out and overexpressing components of Hh signaling pathway\, we fu
 rther demonstrate that Hh signaling is necessary and sufficient for Cerber
 us expression and that disruption of Hh signaling caused defects in left-r
 ight asymmetry. This is different from the situation in vertebrates in whi
 ch Hh signaling is required for maintaining asymmetric expression of Nodal
 \, but not required for Cerberus expression. Together\, our results indica
 te that the core regulatory cassette controlling left–right asymmetry wa
 s in place in the ancestor of amphioxus and vertebrates\, although importa
 nt modifications are also found in amphioxus.
LOCATION:Part II Lecture Theatre\, Department of Zoology
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