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Recent evidence has shown that fruit fly adults and larvae are heavily attracted to food sites occupied by larvae. This attraction is especially strong in mated females that are looking for a suitable site for egg laying. In the first set of experiments, we compared the value assigned to social information provided by larvae at a site to the nutritional information that a female has access to by sampling a food. Lowering food quality did decrease egg-laying preference for a food, but females still showed a much stronger preference for occupied foods. We theorized that the social egg-laying preference may be due to an advantage of developing near older larvae. However, eggs that developed near larvae showed lower survival to adulthood, slower development time, and lower adult body mass. Females were also not able to reduce their social egg-laying preference, even when foods were already heavily occupied by larvae. Finally, we found that larvae were not better able to identify a high quality food site than an adult female, and thus the smell of used food was not a reliable cue to the quality of a site. These results provide evidence that the preference for females to lay eggs near larvae is very robust but the exact benefit it provides for the female and her offspring is unknown. We then ran a series of experiments to test larval social information use to see if they value it as heavily as adult females. Our experiments consisted of focal larvae being put on lower quality food and trying to find a higher quality food nearby that was either occupied or unoccupied by a single model larva. Larvae did not reliably use this social information. Overall, it is unclear whether the larvae are using social information to help them find higher quality foods. / Thesis / Master of Science (MSc)

The reliability of biomarker discovery by means of proteomics has been called into question. It was speculated that "background noise" variation resulting from differences in preparation and handling of samples and proteome dynamics may mask subtle, yet important, differences due to the biological condition. Little is understood about complex proteomes and their variability. A critical aspect of proteomic biomarker research that is largely unexplored is the comparative reproducibility of certain methods such as two-dimensional gel electrophoresis and liquid chromatography/mass spectrometry. In particular, with liquid chromatography/mass spectrometry, it is not known whether variability in peptide quantitation is dependent on any of their several properties such as size, abundance, or hydrophobicity. Such determinations may be critical in properly assessing the value of proteomics data. The fruit fly Drosophila melanogaster was used as a well-controlled multicellular animal model to study the relationship between the background variation and expected changes induced by environmental or genetic factors. The data, gathered by two different proteomics methods, were used to compare and evaluate the reproducibility of the methods. It is reported that there was on average 15 to 18% variability in quantitative measurements of protein abundance using 2-dimensional gel electrophoresis or liquid chromatography/mass spectrometry. Using liquid chromatography/mass spectrometry, peptides with a smaller mass-to-charge ratio were shown to be measured less reproducibly than peptides with a larger ratio. Statistically significant proteomic differences between fly populations could be demonstrated between males and females. In dynamic experiments, less than 0.5% of proteins measured were shown to change after 24 hour starvation of the flies. However, no significant difference in peptide composition could be found for flies fed on a second diet consisting of the standard diet augmented with 10% ethanol. These results suggest that proteomic variability while evident allowed for biomarker discovery using either method for this model system.

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No description available.

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<p> Forty iso-females lines of Drosophila melanogaster were surveyed by SDS-PAGE for length polymorphisms in their heat shock proteins. None was observed. The 70K and 27K HSP's were further analyzed by peptide mapping using Staphylococcus aureas va protease, acid hydrolysis and chymotrypsin. Again, no variation was observed. </p> <p> Thirty-seven species of Drosophila were surveyed for length variation in their heat shock proteins by SDS-PAGE. No variation was observed in HSP84 or HSP70 among any of the species. HSP36 was shown to vary in mobility only, especially among species from different species groups. The small HSP's showed the greatest interspecies variation, especially in the Repleta and Virilis groups. This variation included mobility and band number differences. </p> <p> The results from the 36K HSP's were used to construct a Drosophila species group phylogeny. These groups, shown in descending order of age, are Saltans, Victoria, Melanogaster, Willistoni, Repleta, and Virilis. </p> / Thesis / Master of Science (MSc)

Twenty-five different iso-chromosomal III lines of Drosophila melanogaster, with known haplotypes, were mixed and selected on malaoxon over twelve generations in order to find the importance of variants already present in the Drosophila genome relative to new mutations in the evolution of insecticide resistance. Measurements of mixed function oxidase and acetylcholinesterase activities, as well as insecticide resistance, were made over the twelve generations of selection and on the the iso-chromasomal III lines extracted after the selection was completed. These measurements were compared to those made of the twenty-five lines before selection. This comparison indicated that 52A, one of the origional twenty-five lines, may have been selected during this experiment. Comparisons of a possible cytochrome P-450 produced by a previously selected line of Drosophila called D23, and the DNA which is probably responsible for the production of this P-450, with the microsomal proteins and total genomic DNA of the selected lines were made using the techniques of Western and Southern blotting. The results of these procedures suggested that the mechanism of resistance used by the selected lines was not the same mechanism of resistance used by the D23 line. / Thesis / Master of Science (MSc)

<p> The relationship between the mixed-function oxidase (MFO) system and resistance of Drosophila melanoqaster to phosmet (ImidanR) an organophosphorus insecticide has been studied. The MFO activity was assayed by 7-ethoxycoumarin-O-deethylase (7-ECD) activity and resistance levels were determined by either adult LC- 50 or percent adult survival at 150 uM of Imidan. Two groups of isofemale lines sampled from Vineland, Ontario and a laboratory selected population were used to study variability of the MFO system and its relationship to variability in resistance. </p> <p> A significant positive correlation was found between 7-ECD specific activity and an antigenic determinant assayed by western blotting. The antiserum used to detect this determinant was prepared against a cytochrome P-450-enriched fraction from a malathion-resistant Drosophila melanoqaster strain by J. Pursey (1989). The antigenic determinant was contained on polypeptide P2, believed to be a cytochrome P-450 by its molecular weight and heme content. </p> <p> Laboratory selection on Imidan resulted in over 2 .1-fold increase in resistance. Two MFO activity groups were identified among isofemale lines established from nature. A siqnificant positive correlation was found between 7-ECD specific activity and resistance to Imidan among the Isofemale lines. The minimum number of genes controlling the difference in 7-ECD specific activity between two isofemale lines was estimated to be about 1. </p> <p> It was concluded that this natural Drosophila melanoqaster population has a major or few .genes on chromosome 3 affecting MFO activity and resistance but as well other factors on chromosomes 1 and 2 also contribute to variability in resistance. </p> / Thesis / Master of Science (MSc)