Yip, Man Lun Richard (1995) Molecular genetic analysis of morphogenesis in Drosophila : functions of the hindsight locus. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-10262007-093418
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In order to form complex three-dimensional body structures, multicellular organisms have to be able to coordinate the activities of all cells involved; in metazoa the control of various morphogenetic movements during gastrulation are particularly important. Drosophila embryogenesis provides an excellent model. The Drosophila hindsight gene function is required for germband retraction. Embryos lacking hindsight activity have a normal body plan and undergo normal morphogenetic movement prior to the onset of germband retraction. However, they fail to retract their geinubands. hindsight encodes a large nuclear protein of 1920 amino acids. Sequence analysis reveals that it contains fourteen [...] type zinc-fingers, arranged in widely spaced clusters. Additional features of the HINDSIGHT protein, such as glutamine-rich and proline-rich domains, suggest it functions as a transcription factor. Embryonic expression of hindsight is complex: it is found in the endoderm (anterior and posterior midgut), amnioserosa, subsets of the central nervous system, the peripheral nervous system and the tracheal system. However, it is the expression of hindsight in the midgut that is important for germband retraction since mutations which abolish hindsight endodermal expression also affect germband retraction. Although hnt is not expressed in ectoderm, it is these cells that undergo the cell shape changes that accomplish germband retraction. We propose that hindsight activity regulates a signal produced by the endodelin that is responsible for the coordination of morphogenetic cell shape changes and movements in ectoderm. In addition, hindsight is also required for normal eye development. HINDSIGHT protein is initially detected in the morphogenetic furrow of the developing Drosophila eye. HINDSIGHT is expressed in all photoreceptor cells as they are recruited into the ommatidial cluster. Mosaic analysis of hindsight in the larval eye disc reveals that homozygous hindsight mutant patches contain regularly spaced ommatidial clusters with variable numbers of photoreceptor cells. Analysis of these photoreceptor cells using cell-specific and general developmental markers indicates that their differentiation is abnoiinal. The presumptive R8 cells fail to express BOSS protein and the presumptive R2-5 cells do not express ROUGH protein. Genetically, hindsight shows synergistic interaction with Star, a gene also involved in photoreceptor specification. Taken together, these results demonstrate an early role for hindsight in photoreceptor development. Furthermore, hindsight is expressed throughout eye development and its activity is required late in pupal development when photoreceptor cells undergo morphological changes, such as apical-basal extension and rhabdomere separation.
|Item Type:||Thesis (Dissertation (Ph.D.))|
|Degree Grantor:||California Institute of Technology|
|Thesis Availability:||Restricted to Caltech community only|
|Defense Date:||19 May 1995|
|Default Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Imported from ETD-db|
|Deposited On:||07 Nov 2007|
|Last Modified:||26 Dec 2012 03:07|
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