Cilia are one of the oldest and most well conserved cellular organelles. Cilia provide an essential role in cellular locomotion, fluid regulation, and are a site for signal transduction pathways involved in sensation. A new study suggests that XAP5 is a transcription factor in a unicellular organism, Chlamydomonas reinhardtii, which regulates gene expression needed for proper cilium assembly. Our study investigates the conservation of the role of XAP5 in a multicellular system, Caenorhabditis elegans. Alignments between protein, coding region, and promoter sequences for XAP5 orthologs from related species show a good conservation in DNA and protein sequences. As part of the million-mutation project, we obtained a strain, VC40591, which carries a mutation in a gene corresponding to xap-5 (CExap5). To remove unwanted mutations we “backcrossed” our strains twice to replace mutant chromosomes with wild type chromosomes. Backcrossed strains containing CExap5(gk709587) showed chemosensory and dwelling defective patterns, similar to C. elegans with known ciliary deficiencies. Furthermore, a dye-filling assay showed an irregular pattern of dye filling in the tail and sometimes in both the head and tail, at multiple stages of development. However, CExap5 mutant worms typically showed dye filling in the adult stage. Difference at multiple life stages suggest a developmental problem that must be further studied. Overall, our results indicate that CE-XAP5 confers a loss-of-function phenotype consistent with a cilia deficiency, which might suggest a conservation in function with its orthologous protein.
Level of Honors
Beth De Stasio
Vazquez, Nabor, "Novel Characterization of the Role of Orthologous XAP5 in Caenorhabditis elegans" (2019). Lawrence University Honors Projects. 133.
Available for download on Thursday, May 28, 2020