Universität zu Köln

Wang, Ruixun ORCID: 0009-0002-2943-6898 (2026). Molecular and Morphogenetic Analysis of Body Axis Formation in the Spider Parasteatoda tepidariorum. PhD thesis, Universität zu Köln.

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Abstract

Parasteatoda tepidariorum (Pt) rely on cell migration to establish the dorsal–ventral (DV) axis. The migrating cell clusters, or the “cumulus”, originate from a primary thickening region in the germ disc centre, exhibiting features similar to the “Organizer” in frogs. Early studies identified key genes in the region, including Ets4, which is necessary for maintaining cumulus integrity, and the establishment of the DV axis. This thesis aim to address the underlying mechanism. From videos and staining images, it is suggested that the primary thickening structure formed at 18-21 hours after egg laying (hael) through cell invagination. By 24 hael, the internalised cells differentiated into Ets4⁺ cells in the centre and uneven dispersed Ets4⁻ cells in the surrounding. This asymmetric cell patterning may result in asymmetric fgf8 expression in the germ disc at ~30 hael, which guide the cumulus movement after 30 hael. RNAseq analysis on primary thickening cells at ~29 hael from WT and Ets4 RNAi embryos, selected 800 genes. Some of the genes were examined with in situ hybridisation and RNAi test. It is suggested that Ets4 is the upstream of many cytoskeleton regulation and cell movement related genes. Ets4 influences the expression of genes from conserved developmental pathways (Wnt, Hh, Bmp, Notch and Fgf). And downstream genes of Ets4 always function in the invagination, cumulus migration and dorsal opening processes. Specifically, twi RNAi embryos showed no cumulus migration and formed tube-shaped structures with no DV axis. Taken together, a clearer view of early developmental events in Pt is reached, about the formation of the primary thickening and the cumulus. The gene Ets4 is key to both processes, perhaps through its the central hub role in controlling cytoskeleton-related pathways, and its function in regulating cell differentiation pathways. Later, alongside the cumulus movement, proper signals are spread in the germ disc to generate the body pattern.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Wang, Ruixun rwang5@uni-koeln.de https://orcid.org/0009-0002-2943-6898 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-804160
Date:	2026
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Biology > Institut für Entwicklungsbiologie
Subjects:	Natural sciences and mathematics Life sciences
Uncontrolled Keywords:	Keywords Language Parasteatoda tepidariorum English dorsal-ventral axis formation English Ets4 English
Date of oral exam:	21 July 2025
Referee:	Name Academic Title Pechmann, Matthias PD
Projects:	Deutsche Forschungsgemeinschaft (DFG) - Project number 422268363
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/80416