Date of Award

Fall 2012

Degree Type

Thesis

Degree Name

Master of Biological Science (MBioSci)

Department

Biology

Supervisor

Bhagwati P. Gupta

Language

English

Abstract

The expression of lin-11 is regulated by enhancers located upstream from, as well as within, lin-11 intronic sequences. Multiple regulatory inputs control the spatiotemporal expression pattern of lin-11. To better understand that process, we have investigated these regulatory enhancers by dissecting two of the biggest intronic sequences of lin-11: intron 3 and intron 7. Using microscopy, we show that the expression of intron 3 is required in ten head sensory neurons and that the expression of intron 7 is required in two head neurons. The truncation of intron 7 revealed that its regulatory sequence may be located within its narrow 98 base pairs (bp) region. We used bioinformatics to predict which putative transcription factor(s) may regulate AVG expression. Using a hypersensitive RNAi mutant strain, eri-1; lin-15b, we tested forty putative transcription factors and quantitated the number of animals in which the molecular marker lin-11::GFP expression is knockdown in AVG interneurons.

Using electrotactic behavioral analysis we show that the speed of lin-11 null allele, n389, is reduced by almost 50%, when compared to that of the wildtype animals, due to amphid sensory neuronal deformities. We determine which conserved domains of lin-11 are required for the proper development of the neuronal and vulval cells via microinjection rescue experiments.

We sequenced eleven lin-11 alleles to determine which conserved domains are affected and the role of each of these domains in the development of vulval and neuronal cells. Our findings suggest that all lin-11 conserved domains are required for proper vulval cell differentiation as well as for proper development of the amphid sensory neurons. Finally, using tissue specific markers we label vulval cells in lin-11 mutants to show that those cells are defective, as judged by the lack of fate-specific markers in the vulval cells.

McMaster University Library


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