This manual has been designed for a class of twenty- four students concurrently enrolled in the lecture course. The laboratory aids in the learning process and fosters an interest in the science of genetics. This manual and the experiments contained within are both informative and fun. The manual correlates with and expands upon the genetics course. Each investigation, with the exception of the Drosophila melanogaster project, can be completed in a 3-4 hour timeframe. This manual provides a “hands on” experience of theories simply discussed in the lecture course. This manual is intended to be a one-source manual where each investigation is designed to include an adequate introduction. Special attention has been given for each investigation with both the student and instructor in mind.

For organisms undergoing a developmental process it is ideal that specific genes are induced and repressed at the correct time and to the correct level in a coordinated manner. The process of meiosis and spore formation (collectively known as sporulation) in Saccharomyces cerevisiae provides a convenient system to elucidate transcriptional mechanisms of gene repression and the contribution such repression mechanisms offer to cells capable of undergoing a developmental process. This thesis focuses on transcriptional repression of sporulation-specific genes during both vegetative/mitotic conditions and sporulation. The fitness contribution of transcriptional repressors that regulate sporulationspecific genes during vegetative growth were investigated considering the similarities between meiosis and mitosis such as DNA replication, chromosome segregation and cytokinesis. Well-characterised sporulation genes of different functions were expressed in vegetative cells and ectopic expression of these genes was found not to be lethal. It was ascertained through strain competition studies that ectopic expression of the genes IME1, SMK1, SPR3 and DIT1 during mitotic growth did not affect cellular fitness. The expression of NDT80 in vegetative cells, however, caused a marked reduction in fitness and cells were also further compromised in the absence of the Sum1p repressor that regulates NDT80 transcription. The role of NDT80 as a transcriptional activator of middle sporulation genes, rather than the over-expression of NDT80 as a protein, caused the reduction of cell viability. Transcriptional regulation of the middle sporulation-specific gene SPR3 by the meiosis-specific Set3p repressor complex was investigated using synchronous sporulation cultures of the W303a/?? strain commonly used for sporulation studies. In a mutant W303a/?? ??set3/??set3 strain, lacking a key component of the Set3p repression complex, the transcription of SPR3 was uncharacteristically expressed at higher levels and derepressed during late sporulation. This SPR3 expression was consistent for both SPR3 transcript and SPR3::lacZ reporter protein studies. This preliminary work will enable future studies, using SPR3 promoter deletions fused to a lacZ reporter, aimed at determining the region of the SPR3 promoter that the Set3p complex may interact with to transcriptionally repress the gene during sporulation.

For organisms undergoing a developmental process it is ideal that specific genes are induced and repressed at the correct time and to the correct level in a coordinated manner. The process of meiosis and spore formation (collectively known as sporulation) in Saccharomyces cerevisiae provides a convenient system to elucidate transcriptional mechanisms of gene repression and the contribution such repression mechanisms offer to cells capable of undergoing a developmental process. This thesis focuses on transcriptional repression of sporulation-specific genes during both vegetative/mitotic conditions and sporulation. The fitness contribution of transcriptional repressors that regulate sporulationspecific genes during vegetative growth were investigated considering the similarities between meiosis and mitosis such as DNA replication, chromosome segregation and cytokinesis. Well-characterised sporulation genes of different functions were expressed in vegetative cells and ectopic expression of these genes was found not to be lethal. It was ascertained through strain competition studies that ectopic expression of the genes IME1, SMK1, SPR3 and DIT1 during mitotic growth did not affect cellular fitness. The expression of NDT80 in vegetative cells, however, caused a marked reduction in fitness and cells were also further compromised in the absence of the Sum1p repressor that regulates NDT80 transcription. The role of NDT80 as a transcriptional activator of middle sporulation genes, rather than the over-expression of NDT80 as a protein, caused the reduction of cell viability. Transcriptional regulation of the middle sporulation-specific gene SPR3 by the meiosis-specific Set3p repressor complex was investigated using synchronous sporulation cultures of the W303a/?? strain commonly used for sporulation studies. In a mutant W303a/?? ??set3/??set3 strain, lacking a key component of the Set3p repression complex, the transcription of SPR3 was uncharacteristically expressed at higher levels and derepressed during late sporulation. This SPR3 expression was consistent for both SPR3 transcript and SPR3::lacZ reporter protein studies. This preliminary work will enable future studies, using SPR3 promoter deletions fused to a lacZ reporter, aimed at determining the region of the SPR3 promoter that the Set3p complex may interact with to transcriptionally repress the gene during sporulation.