Work

The Halloween gene shadow is involved in embryonic development and postembryonic molting in the spider Parasteatoda tepidariorum

Year: 2026

Type: article

Abstract: Ecdysteroids are key hormones that regulate molting and developmental processes in arthropods, including insect metamorphosis. Understanding the molecular roles of the genes involved in ecdysteroid biosynthesis could provide crucial insights into the evolutionary conservation of regulation and regulatory modifications in arthropods. While extensively studied in insects, the functions of the so-called Halloween genes, encoding enzymes responsible for the conversion of cholesterol to ecdysone and 20-hydroxyecdysone, remain unclear in arachnids. Therefore, this study aims to elucidate the functions of the Halloween gene shadow ( Pt-sad ) in the spider Parasteatoda tepidariorum in both embryonic and postembryonic stages and to assess its potential role in molting. In situ hybridization was employed to characterize the expression patterns of Pt-sad , and RNAi-mediated knockdown (RNA interference) was conducted to explore its effects on development and molting. Knockdown of Pt-sad resulted in increased embryonic mortality and developmental delays, while it disrupted molt cycles in the postembryonic stages, supporting a role in ecdysteroidogenesis. Expression analysis revealed Pt-sad activity in specific regions of embryos and juveniles, including the central nervous system, appendages, and circulatory system. These findings highlight the multifunctionality of shadow in the spider. While the involvement of this gene in the ecdysteroid pathway is most likely conserved in arthropods, this role may have diversified in spiders to include additional, unique functions that differ from their insect counterparts. • Pt-sad is dynamically expressed in neuroectoderm and circulatory system. • Expression indicates multifunctionality in embryonic and postembryonic stages. • Parental RNAi results in increased embryonic mortality and developmental delays. • Postembryonic knockdowns result in molting defects, suggesting a role in ecdysis.

Source: Developmental Biology

DOI: 10.1016/j.ydbio.2026.02.010

Authors: Denise Klinkenbuß, Sandra Treffkorn, Georg Mayer, Nikola-Michael Prpic

Institutions: Justus-Liebig-Universität Gießen, University of Warsaw, University of Kassel

Language: English

Topic: Neurobiology and Insect Physiology Research

Subfield: Cellular and Molecular Neuroscience

Field: Neuroscience

Domain: Life Sciences

Open Access status: hybrid

Estimated APC paid: $3,550

Funders: Justus Liebig Universität Gießen, Deutsche Forschungsgemeinschaft, Universität Kassel