Access Type

Open Access Thesis

Date of Award

January 2022

Degree Type

Thesis

Degree Name

M.S.

Department

Biological Sciences

First Advisor

Aleksandar Popadic

Abstract

Scent glands (ScGs) are defensive glands that are found among a wide variety of insect orders. These glands represent a specialized function of the exocrine system; however, the developmental mechanism remains unclear. Previous functional studies of the endocrine glands revealed that the endocrine and tracheal systems utilize similar genetic regulatory networks which indicate that these systems have common primordia. In Drosophila, sal is localized in the prothoracic gland while in Oncopeltus the gene is localized in the duct cells of the abdominal scent glands (Hanna & Popadić, 2020; Sánchez-Higueras et al., 2014). RNAi mediated knockdown of sal resulted in significant reduction of the abdominal ScG in nymphs and the metathoracic (Mtx) ScG in adults. Interestingly, there is no localization of sal in the thoracic segments, indicating that the activation of sal on the Mtx ScG is temporally restricted to later developmental stages. Linked by their lipid metabolism function, as ScGs secretions are largely composed of hydrocarbons, oenocytes served as a possible ancestral precursor to ScG. Studies on oenocytes show that genes involved in ScG and endocrine gland development are involved in their differentiation (Burns et al., 2012; Gould et al., 2001; Makki et al., 2014). HNF4, an oenocyte marker, was found to localize in the embryonic abdominal ScG in addition to the gut and pleuropodia. These results provide further clarification on the genetic regulatory network of ScG development.

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