The Regulation of Commissureless in the Embryonic CNS of Drosophila melanogaster

Bibliographic Details
Main Author:	Jowdy, Casey C.
Language:	English
Published:	The Ohio State University / OhioLINK 2010
Subjects:	Biology Genetics Molecular Biology
Online Access:	http://rave.ohiolink.edu/etdc/view?acc_num=osu1284172382

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spelling	ndltd-OhioLink-oai-etd.ohiolink.edu-osu12841723822021-08-03T06:00:46Z The Regulation of Commissureless in the Embryonic CNS of Drosophila melanogaster Jowdy, Casey C. Biology Genetics Molecular Biology <p>During development the precise wiring of the nervous system is dependent on thecorrect repertoire of axon guidance molecules being expressed at the right time and place.In the CNS of D. melanogaster, Comm and Robo play important roles in regulatingaxons at the midline. To date much has been studied about how Comm regulates Robo,but little is known about how Comm is regulated in the CNS. Comm is dynamicallyexpressed in an off, on, and off again fashion in contralaterally projecting axons and isnot expressed in ipsilateral projecting axons. Our hypothesis is the dynamic spatial andtemporal regulation of Comm is at the transcriptional level.</p><p>In our attempt to understand the molecular basis of Comm expression, we haveundertaken several approaches to identify the necessary cis-regulatory elements.Experiments using large P[acman] rescue constructs fail to restore proper Commexpression in the CNS, suggesting that the cis-regulatory regions for Comm may be quitelarge. To further our understanding of these potentially large cis-regulatory regions, wehave taken advantage of site-specific recombination using the yeast enzyme FLPrecombinase and FLP recognition target (FRT) sites to make molecularly defineddeletions. A series of deletions that remove large portions of DNA, as far as 71 kb 5! ofComm and deletions 45 kb 3! of Comm, have been tested with existing comm alleles.Analysis of these deletions using monoclonal antibodies BP102 and 1D4 to reveal axonprojections in the CNS show deletions 5! of Comm have a Robo-like phenotype, whereaxons cross the midline inappropriately. Examination by fluorescent in situ hybridizationfor Comm transcript at single cell resolution using genetically defined markers to reveal asubset of (ipsilaterally projecting) neurons reveals Comm accumulation in the cell bodywhere Comm is not normally expressed. In a subset of commissurally crossing eagle(Ew) neurons Comm accumulation is detected earlier than normal. In summary, we haveidentified the 5! region of Comm as crucial for negatively regulating Comm expression inthe CNS.</p><p>In addition to Comm, there are two Comm-like genes in Drosophila, Comm2 andComm3. Comm3 is expressed too late in embryogenesis to play a role in midlineguidance. However, we show that Comm2 is largely co-expressed with Comm in asimilar pattern throughout embryogenesis. Unlike Comm, deletion of Comm2 has nodetectable BP102 or 1D4 phenotype; a mild Robo-like gain-of-function phenotype isproduced when Comm2 is pan-neurally expressed in the CNS. A screen for dominantmodifiers of the Netrin deficiency phenotype has revealed that large deletions removingboth Comm and Comm2 act as dominant enhancers of the Netrin mutant phenotype.Further analysis demonstrates that mutations in comm and comm2 individually enhancethe Netrin deficiency phenotype, but to a lesser extent than the deletion of both comm andcomm2. This result strongly suggests that Comm2 is playing commissural axon guidanceat the midline. Uncovering the role of Comm2 will contribute to our knowledge of axonguidance decisions at the midline.</p> 2010-11-01 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1284172382 http://rave.ohiolink.edu/etdc/view?acc_num=osu1284172382 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection	NDLTD
language	English
sources	NDLTD
topic	Biology Genetics Molecular Biology
spellingShingle	Biology Genetics Molecular Biology Jowdy, Casey C. The Regulation of Commissureless in the Embryonic CNS of Drosophila melanogaster
author	Jowdy, Casey C.
author_facet	Jowdy, Casey C.
author_sort	Jowdy, Casey C.
title	The Regulation of Commissureless in the Embryonic CNS of Drosophila melanogaster
title_short	The Regulation of Commissureless in the Embryonic CNS of Drosophila melanogaster
title_full	The Regulation of Commissureless in the Embryonic CNS of Drosophila melanogaster
title_fullStr	The Regulation of Commissureless in the Embryonic CNS of Drosophila melanogaster
title_full_unstemmed	The Regulation of Commissureless in the Embryonic CNS of Drosophila melanogaster
title_sort	regulation of commissureless in the embryonic cns of drosophila melanogaster
publisher	The Ohio State University / OhioLINK
publishDate	2010
url	http://rave.ohiolink.edu/etdc/view?acc_num=osu1284172382
work_keys_str_mv	AT jowdycaseyc theregulationofcommissurelessintheembryoniccnsofdrosophilamelanogaster AT jowdycaseyc regulationofcommissurelessintheembryoniccnsofdrosophilamelanogaster
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The Regulation of Commissureless in the Embryonic CNS of Drosophila melanogaster

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