Date of Award
2025
Document Type
Honors Thesis (Open Access)
Department
Colby College. Biology Dept.
Advisor(s)
David Angelini
Second Advisor
Christina Cota
Third Advisor
Robert Augustine
Abstract
optix expression during the larval stages of a caterpillar’s life cycle has been unexplored, as findings of optix are limited to pupal and adult stage caterpillars. optix has a high conserved activator of wing color in the Nymphalidae family. Determining where and when optix is expressed will aid in establishing a comprehensive understanding of wing development and patterning. This thesis aims to observe the physical developments of these caterpillars from hatching until pupation and study optix expression in larval stage V. cardui caterpillars. The developmental atlas of V. cardui caterpillars throughout their larval stage was curated via the daily weights, lengths, molts, and physical descriptions of a sample cohort of ten caterpillars across ten days. A distinct relationship between a caterpillar’s length and molt is observed and identified. optix expression throughout the larval stage was studied using in situ Hybridization Chain Reaction (HCR) on third, fourth, and fifth instar imaginal wing discs to visualize spatially the location and presence of optix expression on larval wing discs. This technique indicated that there is optix expression in all three of these instars and spatially its location changed throughout the instars, therefore supporting the hypothesis that optix is expressed in the larval stages of V. cardui caterpillars. The presence of optix expression in fourth and fifth instar imaginal wing discs was confirmed by qPCR. spalt and decapentaplegic (dpp) were also examined since they are known to play a role in the activation and suppression of optix. in situ HCR showed that dpp overlapped with regions of optix and spalt expression while spalt expression location changed throughout the instars. qPCR results indicate the presence of both genes in fourth and fifth instar imaginal wing discs. The presence of optix at early larval stages and its location towards the distal margin of the wing disc suggests that this gene is important for pigmentation pattern and possibly wing development.
Keywords
developmental atlas, optix, pigmentation, larval, instars, spalt, dpp
Recommended Citation
Hample-Forcier, Chloe B. and Angelini, David, "Exploring the Role of optix Expression in Vanessa cardui through in situ HCR and qPCR and the Creation of a Developmental Atlas of Larval V. cardui Caterpillars" (2025). Honors Theses. Paper 1500.https://digitalcommons.colby.edu/honorstheses/1500
