Date of Award


Degree Type


Degree Name

MS Biology




Carolyn Bentivegna

Committee Member

Allan D. Blake


Biology, Genetic diversity, Balbiani Ring, Genes, Chironomus


Differences in genetic composition have been predicted among aquatic midge fly larva called chironomids. Although several genes including microsatellites and ribosomal protein genes have been explored in our lab, the gene that has so far been studied the most is the Balbiani Ring (BR) 1 gene. There are several genes in this family, including Balbiani Ring 2.1, 2.2 and 6. These BR genes are known to contain long arrays of tandemly repeated units with a ranked repeat organization (Paulsson et al.1992). This secretory protein gene forms a large puff located on polytene chromosome IV (Bentivegna et al., 1993). The gene codes for a protein that when secreted forms the larval tube from which these organisms feed. Organisms within the same Family share similar genetic makeup, therefore understanding variations in a specific gene may prove to be invaluable. By studying this gene, it may be possible to understand the changes that it, and genes like it, undergo when exposed to environmental stressors such as toxicants. Early study of the BR! gene suggested that it contains tandem repeated sequences, which indicates that its genetic evolution is not conserved. This study analyzed DNA from fourth instars of C. tentans and C.riparius. Data was generated using PCR and single­ stranded-conformationa1-polymorphism. Results indicated that double stranded DNAs (dsDNA) from both species were similar in size, between 123 and 246 base pair. The single stranded positive and single stranded minus bands of both species varied however, the minus strand showed more variation than the positive one. This variation was seen between individuals of the same species and between each species. More variation was seen in C. tentans than in C. riparius. The results based on these techniques suggested that there are polymorphisms, genetic variation in the single strand DNA (ssDNA) of each of the species tested.