Regeneration and Transdetermination in Drosophila Imaginal Discs
Another academic year is coming to a close here in France and today @ IBDML we had penultimate external seminar ( every week we have a speaker from outside the institute and Next week we have final talk for this year by Bert Hobmayer ,from Univ of Innsburck ,Austria working with Cnidarians,so a fitting end to the year’s seminars) by Gerold schubiger ,Fred Hutchinson Cancer Research Center, Seattle.In fact i was waiting for this seminar desperately since two weeks and finally it was worth waiting.I am fortunate enough to listen to him for second time,once way back in 2001 (IIT KANPUR) when he visited India for a developmental biology meet. It was great to see the man presenting his work with same enthusiasm ( I don’t know whether i would be able to work in that age) and that inspired me to do work even harder.In his talk he discussed about his two recent papers on Transdertermination in Drosophila wing imaginal discs and his presentation was unique with many old images of Drosophila which i was seeing for first time.
Imaginal Discs are the thin sheet like structures found in larval stages of Drosophila, which are the primodia of various adult appendages.These imaginal discs offers an excellent system for studying Developmental plasticity.All imaginal discs in Drosophila are made up of a layer of columnar epithelium or the disc proper and a layer of squamous epithelium called the peripodial membrane.
Normally during development these discs end up forming respective adult appendages (Wing discs form wing and leg disc in larva gives rise to adult leg) upon metamorphosis, unless given regeneration cue and in these circumstances they may change identity.In Drosophila, imaginal disc regeneration can be induced either by fragmentation and in vivo culture or in situ by ubiquitous expression of wingless.
Regeneration in the disc is mediated by a localized region of cell division, known as the regeneration blastema. Most regenerating disc cells strictly adhere to their disc-specific identity; some cells do switch fate in a phenomenon known as transdetermination. Similar regeneration and transdetermination events can be induced by misexpression of the signalling molecule wingless.Recent work from various labs provided further inputs about plasticity of disc cells during regeneration being associated with high morphogen activity and the reorganization of chromatin structure.
Schubiger’s lab identified three genes, regeneration (rgn), augmenter of liver regeneration (alr) and Matrix metalloproteinase-1 (Mmp1) expressed specifically in blastema cells during disc regeneration which a great step forward in deciphering regeneration concept ,which in-spite of being an important feature (used for maintaining and repairing of tissues) its mechanism is largely unknown.
Reference:
McClure KD, Sustar A, Schubiger G.
Three genes control the timing, the site and the size of blastema formation in Drosophila.
Dev Biol. 2008 Jul 1;319(1):68-77.
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