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dc.contributor.authorNguyen, Duc Nhat Ton
dc.identifier.citationSource: Dissertation Abstracts International, Volume: 58-03, Section: B, page: 1120.;Advisors: Rosemary Reinke.
dc.description.abstractThe Drosophila compound eye provides a unique opportunity to study mechanisms in development. It consists of 800 ommatidial units; each is identically formed in a precise pattern by 8 photoreceptor cells (R) surrounded by non-neuronal support cells. Cell fate determination in the eye relies largely on cell-cell interaction, an essential process in many developmental decisions. The transmission and interpretation of positional information require the expression of signalling cues, surface receptors, and downstream effectors for the execution of a developmental program within a cell. This thesis describes a screen of the X chromosome for viable mutations that disrupt this process. The recovered mutations cause a rough eye phenotype or produce an aberrant deep pseudopupil pattern. The preliminary characterization of these mutants indicates that different stages in eye development are possibly affected, resulting in missing R cells, pigment cells or cone cells. One mutation, {dollar}sidekick\sp{lcub}P1{rcub}(sdk\sp{lcub}P1{rcub}){dollar}, which was isolated as a P-element insertion causing a rough eye, is particular interesting; it causes extra R cell recruitment as a result of neuronal differentiation of the mystery cell. Additional defects include abnormal development of cone cell, pigment cell, and bristle. The analysis of {dollar}sdk\sp{lcub}P1{rcub}{dollar} somatic clones in the adult eye revealed that sdk function is not required in the mystery cell or in any R cells, but rather in the surrounding undifferentiated cells to prevent the neural differentiation of mystery cell. sdk does not appear to act in any known signalling pathway. In addition, the development of the extra R7 in {dollar}sdk\sp{lcub}P1{rcub}{dollar} is independent of boss, a gene required for normal R7 development. Over 90 kb of genomic DNA sequence spanning the sdk gene was cloned and overlapping cDNAs represented a transcript of 9.4 kb. The conceptual sdk ORF encodes a putative transmembrane protein of 2222 aa belonging to the immunoglobulin superfamily. The large extracellular domain contains 6 immunoglobulin repeats followed by 13 fibronectin type III repeats. The cytoplasmic sequence does not appear to have any recognizable motif. The sdk gene showed potential alternative splicing in the first intron position in the untranslated region and in the 9th intron position where a mini-exon insertion occurs in the 13th FnIII repeat. The further genetic and molecular characterization of the sdk gene will provide a better understanding of the diverse role of the IgSF proteins in development.
dc.publisherProQuest Dissertations & Theses
dc.subjectMolecular biology.
dc.subjectCellular biology.
dc.titlesidekick: A member of the immunoglobulin superfamily required for pattern formation in the Drosophila eye

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