Four sibling species of the Drosophila melanogaster species subgroup (D. melanogaster, D. simulans, D. sechellia and D. mauritiana) were used to study genetic variation at the protein level by improved two-dimensional (2DE) gel electrophoresis. Three of the species, D. simulans, D. sechellia and D. mauritiana, are chromosomally homosequential, but their phylogenetic relationship to each other is a subject of controversy. Eight tissues representing adult and larval (developmental stage) and reproductive and non-reproductive tissues were analysed for protein variation. The tissues used were as follows: larval testis, brain, haemolymph, wing disc, and adult testis, accessory gland, male and female brain. Close to 400 protein spots were detected per tissue using this sensitive method. Each tissue was compared between species for protein variation. Protein variation was measured on the basis of qualitative differences (presence/ absence) of the protein spots in six pairwise species comparisons and four-way comparisons. Different levels of protein variation were detected for the same tissues in different species comparisons and each tissue showed different levels of variation in the same species. Different tissue proteins seemed to evolve independently in different species. But there was no evidence of any trend or pattern to show that either larval or adult patterns are more diverged than the other. The variation between tissues rather than developmental stages appears to be the major determinat of the level of divergence. The reproductive tract (testis and accessory gland) proteins showed more variation among species comparison than the non-reproductive tissue proteins. Among the four species, D. melanogaster testis proteins, both larval and adult, showed the maximum divergence. From the results it seems that there is a correlation between the level of reproductive tract protein divergence and the degree of reproductive isolation observed among these species. Among the other three closely related species, the levels of divergence of the reproductive tract proteins are similar, but lower than that of D. melanogaster. The phylogenetic relationship based on 2DE protein divergence showed D. simulans to be closer to D. mauritiana than to D. sechellia. / Thesis / Master of Science (MS)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/23332 |
| Date | January 1990 |
| Creators | Thomas, Shanta |
| Contributors | Singh`, R. S., Biology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
Page generated in 0.0085 seconds