Date of Award
Master of Science (MS)
College of Science and Mathematics
Thesis Sponsor/Dissertation Chair/Project Chair
The act of blood-feeding can be nutritionally rewarding for blood-feeding arthropods. However, blood digestion can release pro-oxidant molecules such as heme and iron at potentially harmful levels. If left uncontrolled, this heme/iron can cause oxidative damage and eventually cell death. This has led to the evolution of various adaptations that protect blood-feeding arthropods against iron- and heme-associated damage. Here I postulate that the signature of this adaptation can be observed in patterns of gene family size. To test this hypothesis, I explore convergent evolutionary expansions and contractions of gene families in distinct lineages of hematophagous insects. Specifically, I compare the gene content present in available genomes from blood- feeding and non-blood feeding arthropods (including outgroup taxa in the Lepidoptera [moths & butterflies]), to identify possible changes in gene family size in the blood-feeding taxa. Of the 206 heme/iron-associated genes identified from the model insect, Drosophila melanogaster, five were overrepresented (potentially duplicated) in the blood-feeding taxa: spook (cyp307A1), spookier (cyp307A2), cytochrome P450 12e1 (cyp12e1), hormone receptor and 51 (Hr51), NADH dehydrogenase (ubiquinone) B16.6 subunit (ND-B16.6), and seven were underrepresented (potentially lost). However, when only Dipteran (fly) and Siphonaptera (flea) genomes were included in the analysis, just one iron gene and one heme gene (NADH dehydrogenase (ubiquinone) PDSW subunit (ND-PDSW) were overrepresented in the blood- feeding taxa. Interestingly, the expanded cytochrome genes are known detoxifiers of many compounds, including heme and iron. More broadly, the analytical approach I employee here could be used to evaluate functional convergence for other phenotypic traits, conditional on the availability of annotated genomic data.
Ceesay, Mbemba, "A Bioinformatics Approach for Evaluating Evolutionary Convergence of Gene Family Size in Hematophagous Insects" (2023). Theses, Dissertations and Culminating Projects. 1202.