http___medlib.mef.hr_1604__2.xml
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Žižić Mitrečić, Marica and Mitrečić, Dinko and Pochet, Roland and Kostović-Knežević, Ljiljana and Gajović, Srećko (2010) The mouse gene Noto is expressed in the tail bud and essential for its morphogenesis. Cells Tissues Organs, [Epub . English abstract The mouse transcription factor Noto is expressed in the notochord and involved in its development. Noto mouse mutants, Noto(tc/tc)(truncate) and Noto(GFP/GFP) (Noto null mutant), exhibit a segmental lack of the notochord in the caudal part of the embryo and subsequent tail truncation in adult animals. In order to address the relationship between the tail bud (the undifferentiated mesenchymal cells in the tip of the embryo tail) and the caudal notochord, Noto(GFP/GFP), a loss- of-function mutant, was analyzed. Taking advantage of Noto(GFP/+) heterozygotes, we could track Noto-GFP-expressing cells from the tail bud over the tail cord to the caudal notochord, and confirm a morphological continuum from the tail bud mesenchyme to the caudal notochord. Loss of Noto affected tail bud morphogenesis: Noto-GFP-expressing cells were scattered in the tail bud mesenchyme. They segregated in the notochord-like structure within the medullary cord instead at the tail cord, which subsequently disappeared. In the tail cord, instead of the notochord, additional lumen of the tail gut was formed. These findings suggest that Noto is involved in both rearrangement and morphogenesis of the tail bud during notochord formation. Actions (login required)
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Žižić Mitrečić, Marica (2012) Uloga gena Noto u razvoju kaudalnog notokorda u zametku miša [The role of Noto in development of the caudal part of notochord in mouse embryo]. PhD thesis, Sveučilište u Zagrebu. Abstract A caudal part of notochord in mouse develops between 10.5 and 12.5 days of embryo development. In that stage, a caudal tip of the embryo contains a compact group of cells referred as the tail bud. Differentiation of the tail bud, which is a remnant of the primitive streak, leads to formation of the tail cord, which gives rise to the caudal notochord and the tail gut. Noto is evolutionary conserved gene and it is active exclusively in the caudal notochord. Mouse line Noto eGFP allows tracing of expression of Noto in heterozygous embryos. Expression of Noto was found in the central part of the tail bud, which was continuous with a fully formed caudal notochord. We showed that the tail bud contains several subpopulations of cells and that their differentiation leads to formation of structures present in the caudal portion of the embryo. Noto eGFP embryos lack notochord in the caudal portion. Tail cord gives rise to the tail gut only, while a ventral portion of the medullary cord gives rise to only few scattered cells which are not able to form a normal notochord. Consequently, somites and secondary neural tube are malformed. Analyses of expression of Noto in the caudal portion of Noto eGFP embryo revealed disturbed distribution of Noto expressing cells in the tail bud. Many of these cells, instead of central axis, populate sclerotome of somites, which leads to a segmental lack of the notochord. This dissertation showed that Noto represents the first known gene marker for the caudal notochord. Presence of such a marker and a specific phenotype of Noto eGFP mouse confirm hypothesis about development of caudal structures from the tail bud mesenchyme. Abstract in Croatian Kaudalni dio notokorda u miša razvija se između 10,5 i 12,5 dana razvoja zametka. Zametak je u tom periodu obilježen prisutnošću kompaktne nakupine stanica u kaudalnom vrhu koja se naziva repni pupoljak. Diferencijacija repnog pupoljka kao post-gastrulacijskog ostatka primitivne pruge dovodi do nastanka repnog tračka kao osnove za kaudalni notokord i repno crijevo. Gen Noto je evolucijski konzerviran gen prisutan samo u kaudalnom notokordu. Mišja linija Noto eGFP omogućila je praćenjem izražaja gena Noto u normalnih heterozigotnih zametaka pokazati izražaj gena Noto u stanicama smještenim u središnjem dijelu repnog pupoljka te pratiti kontinuitet izražaja od repnog pupoljka do zrelog kaudalnog notokorda. Tim nalazom pokazano je kako je repni pupoljak građen od nekoliko subpopulacija stanica te da njihovom diferencijacijom nastaju strukture u kaudalnom dijelu zametka. U Noto eGFP zametaka nedostaje notokord u kaudalnom dijelu zametka. Repni tračak oblikuje samo repno crijevo, dok se od ventralnog dijela moždinskog tračka odvajaju neke stanice koje ne uspijevaju oblikovati notokord. Posljedično, poremećen je izgled somita te sekundarne neuralne cijevi. Analiza izražaja gena Noto u kaudalnom vrhu zametka Noto eGFP homozigota pokazala je da je poremećen raspored stanica koje izražavaju Noto u samom repnom pupoljku. Mnoge od tih stanica se umjesto u aksijalnoj ravnini nalaze u sklerotomu somita, što objašnjava nedostatak notokorda. Značaj ove disertacije je u tome što je pokazala kako gen Noto predstavlja prvi poznati specifični biljeg za notokord u kaudalnom dijelu zametka te da postojanje takvog biljega i nalaz specifičnog fenotipa odgovarajuće mišje linije potvrđuju hipotezu o razvoju kaudalnih struktura zametka diferencijacijom iz mezenhima repnog pupoljka. Actions (login required) Downloads Downloads per month over past year