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SUMMARY:The role of choanocytes in the sponge stem cell system and their s
 uggested homology with choanoflagellates - Shunsuke Sogabe (University of 
 St Andrews)
DTSTART:20180131T130000Z
DTEND:20180131T140000Z
UID:TALK98857@talks.cam.ac.uk
CONTACT:Martin Minarik
DESCRIPTION:Metazoan multicellularity required the evolution of cellular p
 rocesses such as cell differentiation\, cell-cell adhesion and communicati
 on\, along with complex gene regulatory networks and the emergence of a st
 em cell system. Choanocytes\, the collared feeding cells in sponges\, have
  been extensively compared with choanoflagellates due to their morphologic
 al similarities and their capacity to form multicellular structures. Recen
 t studies on the choanoflagellate Salpingoeca rosetta\, revealed many gene
 s shared with metazoans are upregulated only when the S. rosetta cells for
 m colonies. On the other hand\, choanocytes have been suggested as playing
  a part in the sponge stem cell system\, but there has been little progres
 s on understanding the development and general biology of sponge choanocyt
 e chambers. Here\, we have documented the formation and maintenance of cho
 anocyte chambers in the demosponge Amphimedon queenslandica\, using cell t
 rackers and proliferation assays\, showing their dynamic nature in the spo
 nge body. Contrary to previous studies in sponges as well as choanoflagell
 ate colonies\, we found that choanocyte chamber development is not always 
 clonal. After metamorphosis\, choanocytes in these chambers are also capab
 le of dedifferentiating into archeocytes (primary stem cells)\, which can 
 subsequently differentiate into multiple cell types including new choanocy
 tes. We propose that choanocyte chambers in A. queenslandica are playing a
  central role in the stem cell system\, increasing and maintaining the ste
 m cell population. We have also obtained cell-type specific transcriptomes
 \, with a number of analyses between choanocytes and choanoflagellate data
 sets showing no strong evidence of a shared gene repertoire. The results f
 rom our studies suggest that the similarities between choanocytes and choa
 noflagellates are likely the product of convergence\, and it is time we re
 visited their assumed homology.
LOCATION:Part II Lecture Theatre\, Department of Zoology
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